What is Semiconductors: Definition and 204 Discussions

A semiconductor material has an electrical conductivity value falling between that of a conductor, such as metallic copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. Its conducting properties may be altered in useful ways by introducing impurities ("doping") into the crystal structure. When two differently-doped regions exist in the same crystal, a semiconductor junction is created. The behavior of charge carriers, which include electrons, ions and electron holes, at these junctions is the basis of diodes, transistors and most modern electronics. Some examples of semiconductors are silicon, germanium, gallium arsenide, and elements near the so-called "metalloid staircase" on the periodic table. After silicon, gallium arsenide is the second most common semiconductor and is used in laser diodes, solar cells, microwave-frequency integrated circuits, and others. Silicon is a critical element for fabricating most electronic circuits.
Semiconductor devices can display a range of useful properties, such as passing current more easily in one direction than the other, showing variable resistance, and sensitivity to light or heat. Because the electrical properties of a semiconductor material can be modified by doping, or by the application of electrical fields or light, devices made from semiconductors can be used for amplification, switching, and energy conversion.
The conductivity of silicon is increased by adding a small amount (of the order of 1 in 108) of pentavalent (antimony, phosphorus, or arsenic) or trivalent (boron, gallium, indium) atoms. This process is known as doping and the resulting semiconductors are known as doped or extrinsic semiconductors. Apart from doping, the conductivity of a semiconductor can be improved by increasing its temperature. This is contrary to the behavior of a metal in which conductivity decreases with an increase in temperature.
The modern understanding of the properties of a semiconductor relies on quantum physics to explain the movement of charge carriers in a crystal lattice. Doping greatly increases the number of charge carriers within the crystal. When a doped semiconductor contains free holes it is called "p-type", and when it contains free electrons it is known as "n-type". The semiconductor materials used in electronic devices are doped under precise conditions to control the concentration and regions of p- and n-type dopants. A single semiconductor device crystal can have many p- and n-type regions; the p–n junctions between these regions are responsible for the useful electronic behavior. Using a hot-point probe, one can determine quickly whether a semiconductor sample is p- or n-type.Some of the properties of semiconductor materials were observed throughout the mid 19th and first decades of the 20th century. The first practical application of semiconductors in electronics was the 1904 development of the cat's-whisker detector, a primitive semiconductor diode used in early radio receivers. Developments in quantum physics led in turn to the invention of the transistor in 1947, the integrated circuit in 1958, and the MOSFET (metal–oxide–semiconductor field-effect transistor) in 1959.

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  1. R

    A Anisotropy of the effective masses in semiconductors

    Recently, I have received a referee report on my paper in which reviewer states the following: "... in all known direct band gap semiconductors the electron effective mass is isotropic or has a negligible anisotropy in a comparison with the hole effective mass which can have much more...
  2. Roger Dalton

    Dependence of Hall coefficient on temperature in semiconductors

    My first assumption is that the temperature dependence on the mobilities can be neglected, and so we would have: $$R_H(T)= \frac{1}{e} \frac{p_v(T)\mu_h^2-n_c(T)\mu_e^2}{(p_v(T)\mu_h+n_c(T)\mu_e)^2}$$ The expression for the electron and hole densities could be derived from...
  3. rogdal

    A Empirical tight-binding sp3s* band structure of semiconductors

    I'm simulating on code the tight-binding sp3s* bandstructure of certain semiconductors, such as GaAs, AlP, InP, ZnSe, etc. with spin-orbit coupling at a temperature of T = 0 K but I'm having trouble at finding the corresponding spin-orbit splitting parameters. For example, I've found in this...
  4. homeworkhelpls

    I Why is resistivity inversely proportional to resistance for NTC semiconductors?

    Why is resistivity inversely proportional to resistance for NTC semiconductors?
  5. Astronuc

    Perovskite semiconductors for solar photovoltaic cells

    I heard this while driving the other day. Progress On Perovskite Solar Cells | Earth Wise with Randy Simon https://earthwiseradio.org/podcast/progress-on-perovskite-solar-cells/ I wanted to check this out. Si melts at about 2,570°F (1,410°C). I'm not sure about 3000°F (1649°C), which...
  6. D

    B Something strange about doping semiconductors

    Some post involving diodes made me reconsider pn junctions, with I first learned almost 40 years ago. Coming from a chemistry background, something always felt strange, but I could not tell what. Now I realized: While e.g. Gallium arsenide is a semiconductor itself and can be described roughly...
  7. W

    How can you make Ohmic contact with NiSi in semiconductors?

    How NiSi is ohmic contact? Ohm contact occurs when a semiconductor has a lower work function than a metal, doesn't it? NiSi has a larger work function than Ni, so how do you make ohm contact?
  8. I

    Engineering What is the best major for working with semiconductors?

    It'll soon be time for me to choose my major. I was looking for either an Electrical Engineering or a Computer Engineering major, with a minor in maths. What would be the best to work with semiconductor assemblies, in production or in R&D? And what exactly is the difference between EE and CE...
  9. mcas

    Calculate Conductivity Temperature Dependence in Semiconductors

    I have to plot the conductivity dependence of temperature and I have problems with obtaining the right dependency of \mu and n. But let's focus only on carrier concentration first. For n I used the third equation. From what I understand N_D is a constant. I want my plot to look like this: But...
  10. A

    Material Characterization of Semiconductors

    I would like to plan on a postgraduate studies in Material Characterization - Semiconductor; how difficult is this subject since there are a varity of technques to master them properly in order to join the Semiconductor Industry?
  11. F

    B Field distribution in semiconductors

    Hello for everyone. I have a question according the field distribution in the semiconductor while the field effect. According to logic, the field is scrreened due to the field of the polarized carriers like electrons and holes. I know about the Debiye length. And that the field on the infinity...
  12. A

    Silicon and Germanium semiconductor mixtures used in component manufacturing?

    Can Silicon and Germanium semiconductors mixture (chemical reaction) with some other chemical elements (if required) assist in creating new and existing robust electronic components? Si + Ge + ? + ? = Can this assist in quantum computing?
  13. M

    Transparent semiconductors

    Summary:: What is the advantage of transparent semiconductors such as Fluorine doped tin oxide over main semiconductors? What is the advantage of transparent semiconductors such as Fluorine doped tin oxide (FTO) and Indium tin oxide (ITO) over main semiconductors? Please explain the uses of...
  14. Helena Wells

    I Energy of donor or acceptor levels in semiconductors

    How can we calculate the energy of a hole or an electron in p and n type semiconductors? Which are the contributions from different sources we must take into account? I know it is the dopant and base but if we change one of them how that changes it ? Maybe the interatomic distance has...
  15. Helena Wells

    I Fermi level change in semiconductors

    Suppose we have a crystal lattice of doped Si with dopant Boron atoms. The energy level of the holes of the Boron atoms are just some eV above the valence band of Si. My question: If we replace all the Si atoms with Ge atoms will the acceptor level change or not? I don't think it will change...
  16. Helena Wells

    Hall effect in semiconductors

    How does the Hall effect work in semiconductors. Since the there aren't enough availabe energy states in the valence band to hold all electrons trying to move due to the magnetic field the Hall effect must be weaker correct?
  17. A

    A DFT calculations for metal oxide semiconductors and graphene oxide

    I am doing experimental research on metal oxide semiconductors and graphene oxide, I also want to do some theoretical analysis. I am new in theoretical, so I need guidance how to proceed with the simple calculations, like DFT. Is there any authentic book with examples? and also is there any...
  18. Praveen1901

    B P-N junction Semiconductors

    I'm new to semiconductors. While I was studying types of biasing in semiconductors, here's what I read - 'In forward biasing, the width of the depletion region is reduced.' Here's what I thought - Since the potential barrier is reduced in the junction due to external potential, the diffusion...
  19. J

    A Difference of the spin Hall effect in intrinsic and extrinsic semiconductors?

    Hello there, I don't really get the difference between the extrinsic or intrinsic spin hall effect or contribution. As i understand, in extrinsic you have spin scattering by impurities, so its the spin orbit interaction of the spin with its orbit, and this orbit is influenced by an impurity...
  20. Z

    Electrical current in semiconductors

    When a voltage is applied to a semiconductor at RT, the thermally excited electrons in the conduction band can move freely, similarly the hole that is generated in the valance band. Suppose we drop a voltage across the semiconductor. The electrons in the conduction band moves towards the...
  21. C

    Extremely high current effects in semiconductors

    So, let's assume in a theoretical case we have a (semiconductor but not necessarily) device, e.g. a MOSFET, that is perfectly cooled and has zero heat resistance (infinite thermal conductivity), and that it's connected to a perfect heat sink (theoretical abstractions for now, I will come back to...
  22. C

    B Semiconductors confusion

    Assume we have a diode . We connenct the negative terminal of the battery(anode) to the n type region and we connect the positive terminal of the battery to the p type region of the battery.The net force forces electrons to start flowing from the n type region to the p type region.As long as we...
  23. D

    Semiconductors GaN, AlGaN -- Questions about abbreviations

    Hi, I have some chemical abbreviation which I do not understand. Please can you tell me what those abbreviations mean? 1. u-GaN 800nm (C:2E16 at/cm3) (I do not understand what "u" stands for; GaN is Gallium Nitride, 800 nm is thickness of layer, C is concentration of atoms per cm3 but I am not...
  24. Matthew Strasiotto

    Doping semiconductors compounded from various element groups

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  25. Joaco

    Studying Condensed Matter Physics Grade vs Materials Science?

    Hi, I'm an undergrad materials engineering student. I am thinking of studying all the way to a PhD as I'm interested on working in research. Right now I work with Semiconductors and I like the field a lot. However, considering what I'm studying, I want to know if it's a good Idea to look for a...
  26. A

    I P-like states in semiconductors

    Hello, I have read in several textbooks and articles of semiconductor physics that the valence bands are p-like state. So, even in the mathematical calculation in k.p theory, it is widely used, especially to define heavy holes and light holes states. My question is: How acurate is this? Why do...
  27. Marcin H

    Semiconductors - Flat band Diagram vs Equilibrium Diagram

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  28. B

    A Interface states in a PIN diode

    Is the equation used to determine the density of interface states in schottky diodes from capacitance- frequency data applicable to PIN junctions?
  29. Marcin H

    Semiconductors - Carrier Recombination

    Homework Statement A sample of Si at room temperature is doped with acceptors at a concentration of 3E16 cm^-3. An excess electron hole pair density of 1E14 cm^-3 is generated at some time t = 0. At t = 13.9 μs the excess EHP density is measured and found to be 5E13 cm^-3.(A). Does the initial...
  30. Marcin H

    Semiconductors - Energy Band Clarification

    Homework Statement This isn't really a problem, but I wanted some clarification on this topic. In an energy band like the one I drew below, what determines the size of the conduction band and valence band? Etop - Ec and or Ev - Ebot? Is that just a property of the material? Also, how do...
  31. Marcin H

    Semiconductors - Drift/Mobility & Temperature

    Homework Statement Homework Equations The Attempt at a Solution I am having problems with all parts of this problem, but I'll start with part A. Comparing the 2 equations I see that Ca could be 3/2 based off the hint, but I am not sure why or how it would be 3/2 or -3/2. The problem...
  32. M

    Metal thin film adhesion, Au-Si deposition

    What protocol should I use to get a good stable 100nm Au adhesion onto a Si substrate using electron beam evaporation? I've heard talk of primer layers of either Cr or Ti at around 5nm thickness, as the typical way to do it. Which material should I choose? What the advantages or disadvantages...
  33. T

    Intro to Semiconductors Help

    Does anyone know of a good resource for semiconductor physics? I can't find much for it and the textbook isn't much help. Here is a https://filebin.net/8navybb1hnt50wi9/Formulae_2017.pdfandhttps://filebin.net/8navybb1hnt50wi9/Formulae_2017.pdfthe textbook is an introduction to semiconductor...
  34. A

    I Fluorescence from core shell quantum dots

    What is the reason for enhancement in the intensity of emission due to the introduction of a shell in quantum dots? I do understand the blue shift in quantum dots but how does a shell enhance it?
  35. A

    I Exploring the Potential of Higher Beam Energies in Semiconductor Doping

    I have a pressing question, but I don't exactly know how best to articulate, or where. I am a wafer fab operator in the semiconductor industry. I usually operate ion implanters. The highest energy ion beams we use are a little over 3.5 MeV. As an aside, I am looking for a way, given that, to...
  36. bluejay27

    A Why must colloidal quantum dots be semiconductors?

    Couldn't there be conductor quantum dots or insulator quantum dots? Conductors and insulators still have energy bands.
  37. C

    A Cylindrical Poisson equation for semiconductors

    In a cylindrical symmetry domain ## \Phi(r,z,\alpha)=\Phi(r,z) ##. Does anyone can point me what can be found in literature to solve, even with an approximate approach, this equation? \nabla^2 \Phi(r,z)=-\frac{q}{\epsilon} \exp(-\frac{\Phi(r,z)-V}{V_t}) Where ## q, \epsilon, V ## and ## V_t ##...
  38. I

    A Change of ε with pressure for Semiconductors

    In "Sado Adachi" book "Properties of Group-IV, III–V and II–VI Semiconductors" page 222, he reported that "both εs and ε∞ decrease almost linearly with increasing pressure", however i was not able to find any empirical formula to describe these relationship for materials InAs, InP, InSb, where...
  39. M

    Impact of crystal defects on band diagram.?

    I was studying about Crystal defects in crystals and came to know that it has huge effect on band diagram.I don't know about their specific impact on band diagram.So what are major impacts of crystal defects on band diagram.?
  40. H

    Increase the maximum voltage rating of semiconducter

    Hello, I was wondering if there is any way of increasing a transistor or thyristor maximum voltage ratting in DC? Thanks. Edit: Just to be more precise, I am referring to the off state. I know you can the on state via a resistor.
  41. Kara386

    Anderson's rule semiconductors

    Homework Statement An InAs quantum well in AlSb has a bandgap of 1.58eV in AlSb, and a bandgap in InAs of 0.354eV. The electron affinity of AlSb is ##3.65eV## and the electron affinity of InAs is ##4.90eV##. Is this a Type I, II or III heterojunction? Use Anderson's rule. Homework EquationsThe...
  42. bluejay27

    I Which are semiconductors in the periodic table?

    Can combination elements in group I and group VII be a semiconductor? My thinking is that they form the octet rule just like group II and group VI elements.
  43. bluejay27

    B Do quantum dots always have to be semiconductors?

    Are there insulator quantum dots or conductor quantum dots?
  44. bluejay27

    I Heavy metals and semiconductors

    Is there a list of semiconductors that are heavy metals?
  45. A

    I The Mystery of the Fermi Surface & Semiconductors

    My teacher told me the other day that a semiconductor does not have a fermi surface. I didn't understand this remark. As I understand it the Fermi Surface is just the surface in k-space spanned by the highest occupied energy levels. Surely in a semiconductor you will also have some highest...
  46. J

    B Likely replacement of semiconductors

    Soon our ability to continue making ICs more dense will end and we will be forced to come up with new technology for greater speeds and calculating power. In your opinions, what is the most likely technology that will replace (or be integrated in with) semiconductor chips? Photonics...
  47. D

    A Carrier concentration temperature dependence; semiconductors

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  48. mertcan

    Studying Semiconductors for undergraduate and graduate

    hi, I would like to be bursting with semiconductors' topic, I aim to know all it's theory and applications, also see all derivations of it's formulas, so Could you give me some suggestions to comprehend this topic well?
  49. E

    I Number of electrons in conduction band

    Hello! In order to obtain the number of actual electrons in the conduction band or in a range of energies, two functions are needed: 1) the density of states for electrons in conduction band, that is the function g_c(E); 2) the Fermi probability distribution f(E) for the material at its...
  50. E

    I Double heterostructure junction in forward and zero bias

    Hi! When dealing with a pn homojunction, it is easy to see the features it has at equilibrium, and also the features it has with forward/reverse bias. Plots show the constant Fermi level at equilibrium and the different Fermi levels for a forward bias; moreover, examples show how much the bands...