Semiconductor - Science topic

Hi Friend

I'm looking into the same thing. Did you find an answer??

Thank you so much Carlos Ariel Samudio Pérez and Karima Akroud

I did try the tb-MBJ. functional too..still the same.

every time i calcualte the specific capacitence it comes less than 50. dicharge time also comes in 5 to 15 seconds? what is possible reason for this. I am using glassy carobn electrode with 0.07cm2 area?it is the imapct of low mass loading? kindly guide?hihgly appreciated. i am using sp-300 biologic potentiostae and techiques for the GCD is gpcl2?

Hey there Subham Paramanik!

You've Subham Paramanik hit on a crucial point about metal halide perovskites. Their soft lattice and ionic bonds indeed contribute to mixed electro-ionic conduction, making it essential to distinguish between electronic and ionic components.

Fortunately, several experimental methods can help in this regard. One common approach involves impedance spectroscopy, where frequency-dependent measurements can reveal distinct responses from electronic and ionic processes. By analyzing the impedance spectra at different frequencies, one can separate out the contributions of electronic and ionic conductance.

Another method is to employ temperature-dependent conductivity measurements. Since electronic and ionic conductivities often have different activation energies, varying the temperature can selectively enhance one type of conductivity while suppressing the other. This allows for the determination of their individual contributions to the total conductance.

Additionally, techniques such as Hall effect measurements and transient current analyses can provide valuable insights into the nature of charge transport, aiding in the separation of electronic and ionic conductivities.

By combining these experimental methods judiciously, researchers can effectively disentangle the electronic and ionic contributions to the overall conductivity in metal halide perovskites, paving the way for a deeper understanding of their fascinating properties.

Hope this helps! If you Subham Paramanik need more details or have further questions, feel free to ask. Let's dive deeper into this fascinating topic!

Check out the reference list in this online article:

Advanced ceramics - the new frontier in modern-day technology: Part I (scielo.org.za)

Dear Pramod Gawal ,

The formation of Z-scheme and Type-II heterostructures in semiconductors involves specific theoretical criteria related to the conduction band (CB) and valence band (VB) potential differences. Let’s delve into the details:

In summary, while there’s no strict numerical threshold, the relative positions of CB and VB levels significantly influence the formation and performance of Z-scheme and Type-II heterostructures. Researchers continue to explore novel combinations and optimize band alignments for efficient energy conversion.

Janak Paudel, Larger bandgap typically corresponds to a lower intrinsic carrier concentration, while a smaller bandgap results in a higher intrinsic carrier concentration. This relationship is due to the energy required to promote electrons from the valence band to the conduction band.

A typical semiconductor is a crystalline solid material with an Electrical Conductivity that is highly dependent on temperature. At low absolute temperatures a pure semiconductor will appear to be a good insulator, however, its conductivity rises dramatically as the temperature increases. Electrical currents are transported by ions in a given solution. As the concentration of ions increases, the conductivity increases. This is because conductivity increases as water dissolves more ionic compounds due to the ions transporting an electrical current in the solution.I t might reduce or improve with temperature. In a metal , when temperature increases the resistance increases , due to which resistivity increases and thus , conductivity decreases . Whereas , in case of a semiconductor with increase in temperature , the resistance decreases and thus the conductivity increases .However, conductivity generally only increases with temperature in semiconductors. In metal conductors, increasing the temperature usually results in a decrease in conductivity, or it increases the resistivity. When temperature increases, the vibration of metal ions increases. This results in increase in resistance of metal and hence, decreases in conductivity. In electrolytic conductors, the ions are charge carriers and with increase in temperature, ionization increases and hence, conductivity increases. In semiconductor electron vibration happen at room temperature. But at very low-temperature electron can not get energy and so it can not vibrate and so current cannot pass, so semiconductor act as an insulator. Thus at higher temperatures a semiconductor exhibits properties closer to those of metals. It is the dramatic change in conductivity due to the excitation of valence electrons into the conduction state as the ambient temperature is increased that is the characteristic feature of a semiconductor.

Useful thing

Most photodectors are silicon and germanium based, and that are indirect bandgap semiconductors. Direct gap semiconductors e.g. GaAs or GaP are used too for suitable wavelength however their problem might be too shallow depth of absorption for some light wavelength because of direct bandgap.

The electrical conductivity of semiconductors increases with increasing temperature because, with increase in temperature, number of electrons from the valence bond can jump to the conduction band in semiconductors. When temperature increases, the vibration of metal ions increases. This results in increase in resistance of metal and hence, decreases in conductivity. In electrolytic conductors, the ions are charge carriers and with increase in temperature, ionization increases and hence, conductivity increases. In the case of semiconductors, as temperature increases, electrons in the valence band acquire sufficient energy to be promoted across the "energy gap" into the conduction band. When this occurs, these promoted electrons can move and conduct electricity. Hence intrinsic semiconductor behaves like an insulator. Hence as temperature increases, more and more hole and electron pairs are generated and after a certain temperature and it will behave as ideal conductors. The general rule says that resistance increases in conductors with increasing temperature and decreases with increasing temperature in insulators. In the case of semiconductors, typically, the resistance of the semiconductor decreases with the increasing temperature. At room temperature some covalent some covalent bond breaks and semiconductor behaves slightly as a conductor. The gap between conduction band and valence band is small in semiconductors. Therefore, electrons from the valence band can jump to the conduction band on increasing temperature. Thus, they become more conducting as the temperature increase. The hotter a material, the more its atoms or ions jiggle about and the harder it is for electrons to wriggle through, which translates into higher electrical resistance. The electrical conductivity of a metal decreases with increase in temperature because the thermal energy increases the collision of electrons and disturbs the free flow.

Hi Sir

An increase in temperature will always affect the semiconductor properties (semiconductors are sensitive to temperature) i.e., reduce the bandgap of the semiconductor where the energy needed for the excitation of electrons will be smaller, which results in reduced open circuit voltage (Voc) and efficiency of solar cells. The solar cell's power output directly depends on quasi-Fermi level separation, i.e., Voc. Though, the decrease in bandgap extends the absorption range and increases the short-circuit current (Jsc) of the solar cell, but also decreases the open-circuit voltage (Voc) of the device, thus a half-and-half situation arises for the optimization of the semiconductor material. So Normally, the standard test condition of solar cells in the laboratory is done at 25 degrees Celsius to avoid temperature effects.

You can also refer this article,

Electrical conductivity increases in semiconductors with increasing temperature, because, as temperature increases, the number of electrons from the valence band is able to jump to the conduction band. The electrical conductivity of an extrinsic semiconductor increases with a rise in temperature such that semiconductors have a negative temperature coefficient of resistance. With increase in temperature of extrinsic semiconductor, minority charge carriers increase because of bond breakage and minority charge carriers may become almost equal with majority charge carriers. Thus, extrinsic semiconductor behaves almost as an intrinsic semiconductor with increase in temperature. Clearly, conductivity significantly depends on majority charge carriers generated due to impurity doping. It means conductivity of metal is highly dependent on free electrons. If we increase the temperature of metal then lattice vibration increase so restrictions in the path of free electrons also increases. So conductivity increase by lattice vibration but decrease due to less flow of free electrons. As the temperature of the conductor rises, the velocity of the free-charged particles increases and the increased temperature also affects the amplitude of vibration due to this the vibration rate of metallic atoms also increases.For metals we have positive temperature coefficient of resistance. For semiconductors we have negative temperature coefficient of resistance i.e. as temperature increases then conductivity increases and resistance decreases. The electrical conductivity of semiconductors increases rapidly with increasing temperature, whereas the electrical conductivity of metals decreases slowly with increasing temperature.

It melts or decomposes as usual.

But before that, conductivity rises.

Because one can show conductivity is product of charge carrier density and mobility. With temperature, mobility drops as charge carriers are more often scattered by thermal vibrations, but carrier density rises as more and more carriers are given thermal energy to break from bond of individual atoms (like electrons breaking from valence band to conduction band)

For metals, bandgap being practically zero for all purposes, charge carrier density is near-saturated from very low tempertaure, and fall of mobility with rise of temperature contributes to losing conductivity with temperature.

But for semiconductors, charge carrier density is far from saturated, so heating up to a very significant extant (I cannot tell whether virtually all of break-freeable charge carriers set free earlier or the semiconductor melts earlier as temperture keeps rising ) raises chrage carrier density much much more than lost mobility. So, heating raises conductivity of semiconductors

Hi, you asked so many questions on Fermi levels that I suggest you read a good solid state physics textbook from any university library. An introduction and overview is also available on Wikipedia here:

https://en.wikipedia.org/wiki/Fermi_level

Thomas

Dr Rajesh Parihar thank you for your contribution to the discussion

Dr Clyde Eisenbeis thank you for your contribution to the discussion

Dr Armin Dadgar and Dr Jan Martin Wagner thank you for your contribution to the discussion

Dr Armin Dadgar and Dr Clyde Eisenbeis thank you for your contribution to the discussion

More current causes higher temperature, which causes more current. This cycle repeats itself is thermal runaway. Ultimately, the semiconductor is destroyed. This discovery implies that a semiconductor can become a superconductor upon carrier doping. Recently, superconductivity was also discovered in boron-doped silicon and SiC semiconductors. The number of superconducting semiconductors has increased. Superconductivity is the property of certain materials to conduct direct current (DC) electricity without energy loss when they are cooled below a critical temperature (referred to as Tc). These materials also expel magnetic fields as they transition to the superconducting state. When a strong current passes through the semiconductor it heats up the crystal and covalent bond are broken. Hence because of excess number of free electrons it behaves like a conductor. Voltage that is too high can cause premature failure of electrical and electronic components due to overheating. The damage caused by overheating is cumulative and irreversible.

Dr Vijay Kumar Bodarya thank you for your contribution to the discussion

Dr Vijay Kumar Bodarya thank you for your contribution to the discussion

Dr Naresh,

I'll ask you directly: are you sincere in your interest in the origins of superconductivity or are you simply posting basic questions, hoping for people to answer, and so boost your RG 'score'?

You have posted literally hundreds of basic questions this year, most of which can be resolved with a Google search.

Why?

Meissner effect: All magnetic fields are reflected back from superconductor (a perfect diamagnet) that holds up magnet that emits the magnetic field in first place (provided the field is not too strong to destroy superconductive state).

Earnshaw's theorem says no STATIC arrangement of electric (or magnetic field) can hold up charges in equilibrium, so the floating doesn't happen for two bar magnets

See

Note these

Hope these helps

Yes, a strong current can damage a semiconductor. Here's why:

Now, let's explore the impact of temperature on electrolytes:

Yes, the voltage of an electrochemical cell (which utilizes an electrolyte) can change with increasing temperature. Here's what happens:

The overall impact on voltage depends on the specific type of electrolyte and the chemical reactions involved in the cell. In some cases, the voltage might increase slightly, while in others, it might decrease or remain relatively unchanged.

It's important to note that excessive temperature increases can also be detrimental to electrolytes. High temperatures can:

Therefore, it's crucial to maintain electrolytes within a recommended temperature range to ensure optimal cell performance and prevent damage.

While "intrinsic semiconductor" is a term used, it's not the only one. Semiconductors can be intrinsic or extrinsic, depending on their doping level:

Now, about the thermal conductivity and its relation to temperature, the statement is only partially true and depends on the material:

Therefore, it's crucial to consider the specific material when discussing the relationship between thermal conductivity and temperature.

The statement that conductivity in a semiconductor varies inversely with temperature is incorrect. In fact, the opposite is true: conductivity in a semiconductor increases with increasing temperature. This is due to the unique band structure of semiconductors.

Here's a breakdown of the relationship between temperature and conductivity for both materials:

Therefore, the relationship between temperature and conductivity is opposite for semiconductors and metals. While semiconductors become more conductive, metals become less conductive with increasing temperature.

Conductivity & Intrinsic Semiconductors:

The conductivity of intrinsic semiconductors does increase with increasing temperature. This happens because:

Doping is intentionally adding impurities to a semiconductor to alter its conductivity. These impurities introduce additional energy levels within the bandgap, creating more charge carriers and significantly increasing conductivity compared to intrinsic semiconductors.

There are two types of doping:

Therefore, both increasing temperature and doping can significantly increase the conductivity of intrinsic semiconductors, but they work through different mechanisms.

Semiconductors behave uniquely when it comes to conductivity compared to conductors and insulators, and here's why their conductivity changes with temperature and impurities:

Therefore, both temperature and impurities play a crucial role in determining the conductivity of semiconductors. By manipulating these factors, we can control the flow of electricity in these materials, making them valuable for various electronic applications like transistors and integrated circuits.

Understanding the Relationship between Resistance, Relaxation Time, and Conductivity:

Resistance (R) is a material's opposition to the flow of electric current. In conductors like metals, this opposition arises due to collisions between free electrons (electrons not bound to specific atoms) and the metal's positive ions (atomic cores). These collisions impede the smooth flow of electrons, causing resistance.

Relaxation time (τ) represents the average time between these collisions. Imagine electrons traveling through a corridor with obstacles. The time it takes for an electron to hit one obstacle and then another defines its relaxation time.

The relationship between resistance and relaxation time is:

R ∝ 1/τ (where ∝ represents "proportional to")

This means as the relaxation time increases (fewer collisions), the resistance decreases (easier flow of electrons) and vice versa.

Conductivity (σ) is the inverse of resistance, signifying a material's ability to conduct electricity. It relates to how easily current flows:

Therefore, from the first equation, we can also say:

Relating Conductivity, Mobility, and Carrier Concentration in Semiconductors:

Semiconductors are materials with conductivity between conductors and insulators. Their conductivity depends on the number and mobility of charge carriers, typically electrons or holes (vacancies where electrons would be).

Carrier concentration (n) refers to the number of charge carriers per unit volume in the material. More carriers generally lead to more current flow, potentially increasing conductivity.

Mobility (μ) signifies the ease with which these carriers move under an electric field. Carriers with higher mobility experience fewer collisions and move faster, enhancing conductivity.

The relationship between conductivity, mobility, and carrier concentration in a semiconductor is:

where:

Therefore, for semiconductors, increasing either carrier concentration or mobility can lead to higher conductivity.

Lower Mobility of Holes:

The mobility of holes in semiconductors is indeed less than the mobility of electrons for two main reasons:

1. Effective Mass: In solids, electrons and holes behave like particles with an effective mass, which can be different from their actual mass. The effective mass often depends on the material's band structure and how electrons interact with the lattice. Generally, the effective mass of holes in semiconductors is greater than the effective mass of electrons. This larger mass makes it harder for holes to accelerate under an electric field, leading to lower mobility.

2. Scattering Mechanisms: Semiconductors have imperfections like dopant atoms and lattice vibrations that can scatter both electrons and holes as they move. However, the way these imperfections interact with each particle can differ. Holes often experience stronger scattering due to their interaction with the surrounding positive ions and the fixed atomic positions they "hop" between. This additional scattering further hinders their mobility compared to electrons.

Conductivity and Temperature in Semiconductors:

The conductivity of a semiconductor, which measures its ability to conduct electricity, is related to temperature in a non-linear way:

Therefore, the overall effect of temperature on conductivity depends on which factor dominates: the increase in carrier concentration or the decrease in mobility. In some cases, the conductivity might initially increase with temperature but then decrease at extremely high temperatures due to the dominance of scattering.

In summary, the lower effective mass and less favorable scattering environment contribute to the lower mobility of holes compared to electrons in semiconductors. Additionally, conductivity in semiconductors exhibits a complex relationship with temperature due to the interplay between carrier concentration and mobility.

Show drafts

volume_up

📷

📷

Relationship between Conductivity and Molar Conductivity:

The statement "conductivity and molar conductivity are inversely proportional" is not entirely accurate. They are related, but not in a strictly inverse proportional way. Here's the clarification:

The key point is that both conductivity and molar conductivity increase with increasing concentration, but not at the same rate. Molar conductivity actually increases more slowly than conductivity with dilution. This is because dilution not only reduces the number of ions per unit volume (decreasing conductivity), but also allows the remaining ions to move more freely (increasing their ability to conduct, hence increasing molar conductivity).

Doping and Conductivity in Intrinsic Semiconductors:

Intrinsic semiconductors are pure materials with relatively low conductivity. Doping, however, significantly affects their conductivity in two ways:

Therefore, doping generally increases the conductivity of intrinsic semiconductors by introducing additional charge carriers and potentially modifying their mobility. The specific extent of the increase depends on the type and amount of dopant used.

The relationship between temperature and resistance is not directly proportional nor inversely proportional. It's a more complex relationship that depends on the type of material:

Therefore, it's crucial to consider the specific material when analyzing the temperature-resistance relationship.

In summary, the relationship between temperature and resistance is material-dependent, and the changes in con

Dear friend Rk Naresh

Let's delve into the captivating world of semiconductor physics, shall we? Transmittance and absorbance are intricately connected. Light can be either transmitted or absorbed when passing through a material. These actions are inversely related, like a seesaw.

Now, let's talk about conductivity, mobility, and carrier concentration in semiconductors. Picture a bustling city street. Conductivity is akin to the flow of cars, while mobility is the speed limit. Carrier concentration illustrates the number of cars (carriers) on the road.

Conductivity is directly tied to both mobility and carrier concentration. Increasing either mobility or carrier concentration enhances conductivity, similar to more cars speeding down a street resulting in heavier traffic. The relationship between mobility and carrier concentration is not always straightforward. Sometimes, increasing carrier concentration can decrease mobility, and vice versa. Like maneuvering through a crowded street: more people may slow you down, but efficient movement can still lead to high conductivity.

Overall, a semiconductor's conductivity relies on the balance between mobility and carrier concentration, similar to traffic flow depending on both car number and speed. Understanding these connections is crucial for developing and fine-tuning semiconductor devices for various applications.

Dr Sukru Aktas thank you for your contribution to the discussion

The impurity contributes to the density of states. Therefore, I would use the well-known expression n = F1/2(mu)R0. Where the carrier concentration is n, F1/2 is the Fermi integral, mu is the chemical potential of electrons, and R0 is the density of states at the point with coordinate x.

I think so. (c)

Dr Armin Dadgar thank you for your contribution to the discussion

Dr Sukru Aktas thank you for your contribution to the discussion

Dr Sukru Aktas thank you for your contribution to the discussion

Conductivity of doped semiconductors usually passes through a maximum and a (shallow) minimum as temperature increases.

For, e.g., boron in Si, the boron accepts electron from Si to produce a hole p:

B <=>B(-) + p(+) .

At high temperatures, the equilibrium is completely shifted to the right (endothermic process), and every boron atom present produces a hole; the number of carriers, [p], is thus fixed to the total B (saturation); the specific conductivity per carrier, however, decreases with the temperature (like in metals).

At lower temperature, boron is only partially ionized, and the 'degree of dissociation' alpha increases with temperature - initially exponentially (freeze-out). The conductivity in this region increases proportionally to [p] = alpha*(total B).

At very high temperatures, the intrinsic conductivity starts to dominate, i.e. Si starts to produce e(-) and p(+) - another exponential growth region.

In metals, the primary reason for this behavior is the increased thermal vibrations of the metal lattice. As temperature rises, atoms in the metal lattice vibrate more vigorously, which impedes the movement of electrons and increases the material’s electrical resistance. Consequently, the electrical conductivity decreases.

In semiconductors, the electrical conductivity is governed by the number of charge carriers (electrons and holes) available for conduction. As the temperature increases, more electrons are excited from the valence band to the conduction band, creating more charge carriers and increasing conductivity.

Alvena Shahid Thanks a lot for your answer. I will check your recommended references.

If you're looking for the one rule to get that, we have to disappoint you. See Inmaurer's answer here, it captures the reality quite well, I'd say:

Divyanshu Mishra Pretty much, unless its too large that it looks like two monolayers.

Dear Yasmi,

you will find at least some information in the papers available freely at:

Best regards.

Philippe.

Dear colleague

using THz pulsed laser has no impact on band structure in semiconductor. However it will allow to control ultrafast phenomena such as time-resolved photoluminescence, carriers spin dynamics etc

regards

Thank you, sir (@Santosh Kumar). Beneficial explanation for me.

Just for the sake of my thirst,

Some layered materials (mainly 2D materials) show semi-metal after the bi- or tri-layer. Can it be possible to form Schottky contact with its monolayer version (semiconducting nature)?

Or do you have to choose it, seeing the high work function and also the zero band gap?

Teymour Seymour Talha-Dean is it possible to deposit the metal as a blanket, pattern it and then do a wet chemical etch? perhaps if the metal is uniformly coated as opposed to having side wall coated PR as is the case in liftoff the metal would have higher integrity to the substrate.

Best of luck.

Hey there Janak Paudel,

To measure and calculate the photoconversion efficiency of a semiconductor photoanode in water splitting, you'll want to follow a systematic approach. Here's a concise breakdown:

1. **Current Density Measurement (J):**

- Use a potentiostat to apply a bias potential to the photoanode.

- Measure the resulting current density.

- This gives you Janak Paudel the photocurrent produced during water splitting.

2. **Quantum Efficiency (QE) Determination:**

- Employ monochromatic light sources to irradiate the photoanode at different wavelengths.

- Measure the corresponding photocurrent for each wavelength.

- Calculate the quantum efficiency using the formula:

QE = (number of electrons generated / number of incident photons).

3. **Electrochemical Impedance Spectroscopy (EIS):**

- Apply a small amplitude AC signal to the photoanode.

- Analyze the impedance response to extract information about charge transfer processes.

- This helps understand the recombination losses and charge transport properties.

4. **Light Absorption Measurement:**

- Determine the absorption spectrum of the semiconductor photoanode.

- Use a spectrophotometer to measure the absorption at different wavelengths.

- Ensure the absorption spectrum aligns with the solar spectrum for accurate efficiency assessment.

5. **Stability and Durability Testing:**

- Evaluate the photoanode's stability during prolonged water splitting.

- Monitor changes in performance over time to assess long-term efficiency.

6. **Energy Diagram Construction:**

- Construct an energy diagram of the semiconductor photoanode.

- Identify band edges, energy levels, and losses to understand the energetics of the water splitting process.

7. **Calculate Efficiency (η):**

- Utilize the collected data to calculate the photoconversion efficiency (η).

Efficiency (η) = (photocurrent × applied potential) / (input light power × 100).

Remember, it's crucial to consider factors like material choice, surface modifications, and environmental conditions. This comprehensive approach should provide valuable insights into the photoconversion efficiency of your semiconductor photoanode during water splitting.

Feel free to dig deeper into each step based on your specific experimental setup and objectives. Let me know if you Janak Paudel need more details on any particular aspect.

Hi colleagues,

Just to contribute to your valuable conversation: when talking about electrons and holes in a semiconductor one generally means two different energy bands. This is always the case in the solar cell science.

The simplest tight-binding model of the electronic energy bands clearly demonstrates that lower bands are more narrow than the upper ones. It straightforwardly follows then that the electron effective mass (clearly determined near energy dispersion extrema) should increase for higher bands.

That's why electrons in a completely filled valence band of an intrinsic semiconductor are expected to be "heavier" than electrons in a conduction band.

It's worth noting that right now we consider electrons in the states with minimum energy in the conduction band and therefore electron mass is positive (=the electron energy increases with changing the momentum value). Just oppositely, when turning to the valence band we deal with the electrons in the states with maximum energy there - near the top of the valence band - and therefore electron mass is negative (=the electron energy decreases with changing the momentum value).

The lack of few electrons in the top of the valence band (either due to their capture by acceptors or because of their transfer to the conduction band after photon absorption) can be described as the appearance of few new particles - holes. They dwell on the exactly same energy dispersion law as their 'parent' electrons - that's why their mass is the same as for electrons in the valence band, but has the opposite sign. Here is how the hole mass becomes positive, similarly to the electron in the conduction band.

Üçlü yapıda eksiton organik yarı iletkenler olduğu gibi inorganik yarı iletkenler de bulunur.

Ahmet Ünverdi I understand the frustration you're facing despite following instructions from the literature. Crack-free PZT thin films during annealing are achieved through strategies like film thickness optimization, substrate considerations, surface pretreatment, and post-annealing treatments, despite variations in materials, equipment, and processes.

Zahida Batool If you know the thickness then you can get the n and k values. If you know, or assume, the n and k values you can get the thickness. You can’t get all parameters simultaneously. It’s easy to get an independent thickness measured, say with a profile gage, and thus get n and k.

سلام.سوال منم هست. جوابش رو پیدا کردید؟

Rohit Nimje

To examine the behavior of the metal-semiconductor junction under various circumstances, use software tools for device simulation and modeling, such as TCAD (Technology Computer-Aided Design) tools.

It may depend on a multitude of factors. The information provided is not exhaustive enough to adequately address the question. Adding a dopant (How? How much?) can significantly affect both the electronic band structure and the crystal structure, as well as the quality of your contacts. Without sufficient details and with no basis for my answer, I doubt that a small doping (if it is indeed small) would affect your band structure to such an extent. However, what is generally observed may not necessarily apply to a specific material like yours. Therefore, I will focus more on the crystal structure, surface roughness, or the quality of the contacts.

Roshan Kumar Singh and Jürgen Weippert Thank you for your reply

You can refer to this paper "Chem. Mater. 2022, 34, 1020−1029". This paper about PbI2 which is an indirect semiconductor in the monolayer. However, with constructing supercell, it looks like to have a direct gap.

Raul Montes Thank you very much for the reply and sorry about the late reply. We were asked focus on Laser doping and see if it is feasible. So, I didn't get to go through the articles you mentioned. Again, thank you for the reply and I will go through the papers in the links.

Elektronegatiflikte elektronun hareketi bir üst bandda boş olan hollere yerleşir. Bunun konumunu önceden tahmin etmek çoğu zaman imkansız olur. Ancak tek bir boşluk olursa oraya yerleşme ihtimali yüksek olur. Geometrik ortalaması mutlak band merkezi konumunu yaklaşık olarak verir. Aradaki uzaklık micron ile ölçülecek kadar küçük olur.

thank you for your answering Rafael Valentin Tolentino-Hernandez

When you apply pressure to a crystal along one direction you modify the distances between the atoms. On that direction the energy becomes higher because the atoms are closer to each other. Indeed the band gap is modified when applying pressure (because the potential of the lattice is changed).

By “doped with silicon” are you referring to doping into the Si material or the dopant is Si?

The latter case is not possible since Si has a valence of four, in order to create p-type in Si-based transistor you need one with one unit less i.e., 3 and for n-type valance will be one unit higher i.e., 5.

many thanks Roberto D'Agosta for your reply

Kuljit Kaur did you carry out photolysis experiments for the pollutant (in absence of semiconductor, only exposure to light)? Could be that the pollutant is highly unstable, or the initial concentration is very low.

Another possibility could be, that your semiconductor in aqueous suspension is slightly unstable thus protonating the suspension, and decreasing its pH value (this can be easily ruled out by preparing a suspension containing distilled water and the semiconductor, and by measuring the suspensions' pH for 1-2 hours).

Yes, applying a positive or negative bias on the gate of certain power semiconductor devices can result in different leakage currents (IGSS - Gate-to-Source Leakage Current). Leakage currents refer to the small currents that flow through the device when it is supposed to be in the off-state (blocking state). The magnitude and direction of the IGSS depend on the type of power semiconductor device and its internal structure. Two common types of devices where the bias on the gate affects the IGSS are MOSFETs and Insulated Gate Bipolar Transistors (IGBTs):

1. MOSFETs:

- For N-channel MOSFETs: When a positive voltage (VGS) is applied to the gate (relative to the source), it enhances the flow of electrons in the channel, turning the MOSFET "on" or into its conducting state. In this case, the IGSS is typically very low because the MOSFET is in the on-state.

- For P-channel MOSFETs: When a negative voltage (VGS) is applied to the gate (relative to the source), it enhances the flow of holes in the channel, turning the MOSFET "on." In this case, the IGSS is also typically very low because the MOSFET is in the on-state.

- For both types, when the gate voltage is zero (VGS = 0), the MOSFET should be off. In this off-state, there is a small reverse leakage current (IGSS) flowing through the gate-to-source junction, which is usually very low but can be affected by temperature and other factors.

2. IGBTs:

- When a positive voltage (VGE) is applied to the gate (relative to the emitter), it enhances the conductivity of the IGBT, and it enters the on-state. In this state, the IGSS is generally low.

- When a negative voltage (VGE) is applied to the gate (relative to the emitter), it reduces the conductivity of the IGBT, but it might not turn off completely, and some leakage current (IGSS) can flow through the device.

It's important to note that the magnitude of IGSS is usually quite small in both MOSFETs and IGBTs when they are in the off-state. However, in high-voltage applications or situations where minimizing power loss is crucial, leakage currents become more critical, and device selection and proper driving techniques become important factors to consider. Additionally, the characteristics of IGSS may vary between different device families and manufacturers.

The differentiation can be ascertained to fermi level. When we have a pure Semi- conductor at absolute zero from theoretical point of view the fermi level is at the middle in the forbidden energy band gap. On doping if the fermi level shifts towards the valence band it's a p type conductor and if fermi level shifts towards the conduction band it is an n type semiconductor.

3 malzeme de farklı veya ortak yarı iletken özelliğe sahiptir. Fakat bu özellikler malzemeden malzemeye farklı üstün özellikler gösterebilir. Önemli olan burada bunların yarı iletken özellik gösterip gösteremeyeceğidir.

To investigate the deposition pattern, it is necessary to position the substrate at different locations. The distance between the precursor and the substrate also plays a crucial role, along with other process parameters. It is important to adjust the substrate placement and optimize the parameters to achieve the desired results.

The band gap of composite material cannot be calculated directly from the band gaps of its constituent materials. The reason is that the band gap of a composite material depends not only on the properties of its constituents but also on how these constituents are arranged, including their size, morphology, interfaces, and spatial distributions.

However, there are experimental and computational methods to determine the band gap of composite material:

It is essential to note that these are complex procedures requiring careful implementation and interpretation.

Dear friend Oualid Boumaza

It's wonderful to have the opportunity to share information with you. It's crucial to understand that while graphene possesses impressive electronic properties like high electron mobility, it does not exhibit inherent superconductivity. Nonetheless, graphene can contribute to improving the conduction of free electrons in specific systems, particularly in semiconductor devices.

Now, let's delve into the realm of ferromagnetic Diluted Magnetic Semiconductors (DMS). These materials are captivating because they combine the characteristics of both ferromagnetism and semi-conductivity. By introducing magnetic ions, such as transition metals, into a semiconductor lattice, localized magnetic moments are created. These moments have the potential to interact with conduction electrons, influencing their behavior within the material.

1. "Graphene: Status and Prospects" - Novoselov et al. (2012), Nature, 490(7419), 192-200.

2. "Graphene: A New Paradigm in Condensed Matter and Device Physics" - Castro Neto et al. (2009), Reviews of Modern Physics, 81(1), 109-162.

3. "Graphene for Spintronics and Magnetic Tunneling Junctions" - Žutić et al. (2006), Journal of Physics: Condensed Matter, 18(49), R753-R769.

4. "Diluted Magnetic Semiconductors" - Dietl et al. (2014), Reviews of Modern Physics, 86(4), 187-251.

My upcoming article can be of your interest:

Also, it tells that doping does not change the physical or chemical structure of the material