Semiconductor Definition and 91 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. M

    Silvaco: "simulator has unexpectedly exited with status -1073741819"

    Hello, I am simulating the process of NMOS construction. as you know, in order to make the LDD, we need two implantations, one before creating oxide spacer and another after creating oxide spacer. at the last implantation, I am facing an error which is shown in the following image: I put...
  2. V

    What's the chemistry behind a semiconductor?

    This is a confusing subject for me. It's like only getting half of the story. Reading physics but not understanding how it works in chemistry makes it nonsense to me. Imagine we are creating a silicon-based semiconductor. They have covalent bonds between them, with each silicon atom having four...
  3. LUFER

    What is the Electromagnetic Cross Section in this plasma deposition process?

    What is Electromagnetic Cross Section? (shock section) Hello, I have a question regarding the manufacturing process of electronic components in the case of the silicon deposition and corrosion process. My biggest doubt is the behavior of the plasma interacting in the reactor, I don't know if...
  4. Mayan Fung

    I Measuring the built-in potential of a pn junction

    I am thinking about the reason why we cannot probe the built-in potential across a diode with a voltmeter. Obviously, a diode is not an energy source, so it is impossible for it to show a voltage reading. After doing some research, I found some explanations and some questions about them. 1. The...
  5. 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...
  6. S

    A Gallium Oxide structure

    I have three questions regarding the material Gallium Oxide. I was reading in several articles and they introduced its structure as it has monoclinic structure and it consists tetrahedral and octahedral structures in it. What I can't understand I can connect this structure to the chemical...
  7. P

    Anisotropic Etching in Semiconductor Fabrication

    I am learning about designing semiconductors but I had some issues understanding some things about the structure of Si. About lattice structure: 1) Why does an FCC has 8 atoms per cell? Doesnt has 14? About wafers 1) I know you can have wafers along different surfaces. What information can I...
  8. P

    Semiconductor -- Conduction and Valence bands

    I am a new to this and I try to understand the basics. So initially once the atoms of silicon come together to form a solid, due to Pauli law no electrons can exist in the same energy state,thus many energy states are formed which together make the bands. My problem starts at this stage where I...
  9. N

    Physics Physics Degrees and Semiconductor Industry (IC Design?)

    Hello there, im a physics student from Germany and currently in my second semester of a Bachelor of science. Lately i have become increasingly interested in woking in the Semiconductor Industry and I am currently reading the book "But how do it Know" by J. Clark Scott and i think it is really...
  10. M

    The effect of temperature on phosphorescence

    I had read somewhere that as the temperature increases, its lifetime decreases. But there was no further explanation. Of course, I don't know if it's true yet.
  11. 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...
  12. Kaushik

    B How does the doping concentration affect the depletion width?

    I do not understand why that is the case. Is there any intuitive explanation for it? Thanks
  13. Mayan Fung

    I Recombination and open-circuit voltage in solar cells

    From the ideal diode model, we can derive the open-circuit voltage (Voc) as: $$ V_{oc} = \frac{nkT}{q} ln(\frac{I_L}{I_0} + 1) $$ where ##I_0## is the dark saturation current and ##I_L## is the light generated current. From the model, if the recombination rate increases, the dark saturation...
  14. halleff

    Diffusion current and carrier concentration equilibrium (unbiased)

    Suppose you have a non-uniformly doped piece of semiconductor (without an applied bias) such that the acceptor dopant concentration Na(x) decreases from left to right (as x increases). In this case, the equilibrium hole distribution p(x) will not be uniform since then there would be a net drift...
  15. Athenian

    I Energy of Conduction and Valence Band in Opposing Directions

    Recently, I have been studying some solid-state physics and I came across this ##E-k## diagram online. Here's an image for reference to what I am referring to...
  16. Dor

    Can the displacement current be equal to and opposite in sign to the conduction current so the total current will be zero?

    If so, what will I measure in the Ampermeter, the zero total current or the value of the conduction current? I was thinking of the following example- a circuit consist of a current source, an Ampermeter, a switch, and a semiconductor. The semiconductor can have both conduction and displacement...
  17. S

    Engineering Light absorption in a semiconductor

    The doped a-Si: H layers in a HIT solar cell do not contribute to the photocurrent. The light they absorb (according to their absorption curve below) is lost. For a doped a-Si: H layer at the front side of the cell that is 25nm thick, what percentage of light at 400nm will be lost due to...
  18. Muhammad Usman

    I Concentration of Impurities in Extrinsic Semiconductor ?

    Hi, I was studying a book on analysis and design of analog integrated circuits. In the book it is mentioned as "For practical concentration of impurities, the density of majority carriers is approximately equal to the density of impurity atoms in the crystal" I researched about it and I found...
  19. C

    Diode operation from reverse bias to zero bias

    Assume we have a closed diode circuit .We connect the n type region of the diode to the positive terminal of the battery.We connect the p type region of the diode to the negative terminal of the battery.The depletion layer is increased.Now we open the circuit.Why the diode returns to its zero...
  20. archaic

    Load resistance in voltage regulator

    Homework Statement [/B] I want to find the minimum resistance ##R_L## so as to maintain ##V_z##(voltage of the zener corresponding to the minimum current ##I_{z_0}##) across the same resistor ##R_L##. Homework Equations ##V_z##(voltage of the zener corresponding to the minimum current...
  21. Jalo

    I Photodiode bandwidth: why does power decrease with frequency

    Hi, I'm studying p-i-n photodiode (PD) at the moment and understand that the photodiode's response will depend on the frequency of the light signal going into it. I am struggling however to understand the concept of bandwidth, and why is it that the photocurrent at the PD decreases with higher...
  22. P

    A Acceptable Atmosphere for CZ/Float-zone Refining

    Both the cz (Czochralski Process), and Float-zone refining of silicon require an inert atmosphere, usually argon. How pure does the argon atmosphere have to be? How high of a vacuum has to be pulled before releasing argon into the tank?
  23. P

    Silicon not heating with induction heater?

    I’m using an inductive heater to try to melt some 99.85% polycrystalline silicon, as would occur in the Czochralski process, but the silicon workpiece is not melting let alone even getting hot. The silicon workpiece is about the size of a playing dice. It becomes conductive at 200 F and becomes...
  24. 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...
  25. D

    Problem finding the distribution of holes in a semiconductor

    Homework Statement Long and thin sample of silicon is stationary illuminated with an intensive optical source which can be described by a generation function ##G(x)=\sum_{m=-\infty}^\infty Kδ(x-ma)## (Dirac comb function). Setting is room temperature and ##L_p## and ##D_p## are given. Find the...
  26. C

    Finding the potential inside a semiconductor

    Homework Statement My question is more about understanding the task itself, not about calculation. I am supposed to use the poisson equation, to derive the potential inside a semiconductor for a barrier with potential height ##\phi_B## and a donator doping with ##N1 > N2##. Then I should use...
  27. Fernando Valadares

    Job Skills How to get into the semiconductor industry

    Hi friends, I'm a brazilian Electronics Engineering undergrad student, going to graduate in 3 semesters. I'm also in the first semester of my Masters in Atomic and Molecular Physics, focused on ab initio simulation of semiconductor crystals (VASP). My main interest is to work in industry in...
  28. P

    Why is silicon not melting?

    I’m using a zvs inductive heater to try to melt some 99.85% polycrystalline silicon, as would occur in the Czochralski process, but the silicon workpiece is not melting let alone even getting hot. The silicon workpiece is about the size of a playing dice, and becomes fully conductive after...
  29. avner yakov

    What the difference between pin and pn diodes i-v curve?

    For my understanding there should be no big difference in i-v curve between regular p-n junction and p-i-n junction, the only difference i can think about is do to the bigger resistance of the intrinsic layer. The curve should look the same only the current will rise little bit slower, because...
  30. Mayan Fung

    Degradation of crystalline silicon solar cells

    Hi there, it is commonly accepted that the lifespan of crystalline silicon solar cells is about 20-30years. And they define the lifespan as when the solar cells efficiency drop to about lower than 10%. However, what are the possible reasons for the degradation? I can only find research papers...
  31. D

    Programs Change of Major from Mechanical Engineering to Material Science

    Hello guys, I received an admit to grad school for Mechanical Engineering, where my focus was initially Thermo-Fluids . I've also enquired about the Material Science department at the University(in the USA), and they are willing to let me transfer to the Material Science department provided I...
  32. Hydrous Caperilla

    B Forward biased diode

    If a diode is connected with P junction with higher voltage and N with low voltage then why is there a potential rise as opposed to the decrease in potential like in battery?
  33. N

    I Drift velocity in P-N Junctions

    When a P-N junction is in reverse bias, the drift velocity of the system increases, so why is there no current flow? Is the drift velocity not connected to the current? Thanks in advance.
  34. 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 textbook is an introduction to semiconductor...
  35. S

    Straight line plot of bipolar transistor - temperature?

    Hey everyone, I'm trying to plot a straight line for a bipolar junction transistor to find the room temperature, T, using my experimental results for the associated base-emitter voltage, ##{V}_{BE}## and collector current, ##I_C##. Here's the equation that I'm using: $$ I_C = α_F {I}_{EO}...
  36. G

    Semiconductor resistor in series with a capacitor -- Energy gap

    Homework Statement Consider a circuit that consists on a resistor of an intrinsic semiconductor R and a capacitor C in series. The voltage between the terminals of the circuit is U, which is an alternated sinusoidal voltage. U1, which is the voltage in the capacitor as a phase difference of 30...
  37. J

    A Interference in electron conductance through e.g. molecule?

    Imagine attaching electrodes to a complex sample, e.g. a semi-conductor or a single chemical molecule, leading to some electric current. Can we decompose this electron flow into local flows? - like locally attaching amperometer and counting what fraction of electrons flow directly between given...
  38. G

    PhD after being in industry (EE)

    Dear members, I am an analog designer and I don't get to do a lot of interesting design work at my job. There is a PhD opportunity that came my way which offers really interesting work (will be in a top tier uni and will be working on project for a world famous research institute). However, I...
  39. T

    B Existence of depletion layer in contact surface

    in a P-N junction diode, in an equilibrium state, a depletion layer forms in the surface of contact of N type and P type. But the problem is, this layer is formed by diffusion of electron to a lower electron density zone. Why does it always have to form right in the contactt surface? when...
  40. B

    How to calculate relative effective mass?

    Homework Statement A simplified E versus k curve for an electron in the conduction band is given. the value of a is 10 Å. Determine the relative effective mass m* / m0. Homework Equations [/B] m* = ħ2 / (d2E /dk2) m0 = 9.11 E-31kg 3. The Attempt at a Solution The second derivative must...
  41. T

    B Forward Bias: Why does width of depletion layer decrease?

    The depletion layer is formed by the movement of electrons from the n to p side and holes from p to n side of the diode. The layer consists of positively charged donor ions close to the n side and negatively charged acceptor ions close to the p side. When in equilibrium,the barrier potential...
  42. J

    Uses of a silicon semiconductor at high temperatures

    We conducted an experiment in which we found the variation in the resistance of a fairly pure silicon sample between temperatures of about 400K to 600K, and we found a value for the energy gap of silicon of our sample. We were comparing the resistance variation with the model...

    A Change in Fermi level with gradient of doping concentration

    In a degenerate n type semiconductor, when the doping concentration has a gradient(say -ve gradient), then how fermi energy level and intrinsic Fermi energy levels will depend upon the concentration gradient? ~If anyone knows anything about it, kindly help.
  44. A

    I Phonon energy in absorption of indirect band gap

    Does phonon required a minimum energy in the absorption process of an indirect band gap, and why?
  45. moenste

    Doped semiconductor material: identify n- p- type

    Homework Statement You are given a small slice of doped semiconductor material but you do not know whether it is n-type or p-type Explain with the aid of a diagram the physical principles of an investigation which would enable you to identify the type. 2. The attempt at a solution I searched...
  46. A

    B What would happen if nothing was like it is

    HI guys! I was thinking... What would happen if the atom were considered the smallest thing of the universe, or just that electrons, protons e neutrons were that? That would impact in semiconductors technologies? Or plasma? Or nanotech? How? Thanks in advance.
  47. U

    I-V characteristics of a diode

    I was doing an experiment to plot the IV characteristics of a diode. I connected a resistor, diode and milli ammeter in series. I connected a voltmeter across the diode. I measured the diode voltage and diode current. When i changed the resistor, I got a different set of diode voltage readings...
  48. campeola46

    Finding n and p of semiconductor given temp, NA, ND, and Ni

    I'm doing independent study on semiconductors to prepare for a future class and I'm having problems with some problems that concern finding the n and p of doped Silicon given only a temperature, NA, ND, and Ni. I understand that n*p=Ni^2, but, given that this means that n does not equal ND (and...
  49. A

    A Fixed effective charge in flat band voltage

    I am having a hard time understanding flat band voltage in MOS capacitor. Please see the picture below about MOS capacitor. Q0 is a fixed effective charge at the surface between oxide and semiconductor and it is positive here. The voltage across the oxide caused by the fixed charge ψox =...
  50. T

    I How is a top gate used to change electron density?

    How is a top gate used to change electron density in 2D semi conductors? I get the principle, you are just shifting the chemical potential by some voltage so that there are more or less electrons in the specific bands. But how is it physically done? Thanks.