Semiconductor physics is the branch of solid state physics that focuses on specific properties of semiconductors. It studies dynamics of different perturbations (mainly electrons and holes) in the semiconductor crystal and the ways to affect it.

learn more… | top users | synonyms

0
votes
1answer
184 views

Carrier Electrons Generation and Recombination Time

When a Electron gets promoted to the conduction band from valence band (In generation) lets say for example in Silicon at room temperature. Is there any way to determine (on average) how long it will ...
1
vote
0answers
57 views

Orientation in GaAs

I can't find the precise definition of what is the orientation of a GaAs lattice. Being the superposition of two fcc lattices (one of Ga, the other of As), I would think that it is the direction of ...
1
vote
2answers
652 views

In the diode equation, why the exponential $\exp$ and the ideality factor $n$ are there? What do they represent & what is their significance?

In the Shockley diode equation, why the exponential $\exp$ and the ideality factor $n$ are there? What do they represent & what is their significance? I have to work on Solar Photovoltaics, and ...
2
votes
2answers
307 views

How can electrons be confined in Quantum dots?

Atoms are in the range of $1$ Angstrom while Quantum dots are in the range of $2$-$10$ nm. In any atom, $99.9$% is unoccupied. So if I have a Quantum dots of size $3$ nm and suppose in my Quantum dot, ...
1
vote
2answers
2k views

Why should the Fermi level of a n-doped semiconductor be below the one of a p-doped?

In a pn-junction, the difference in Fermi level between the p doped and the n doped regions causes the apparition of a built-in electric field at equilibrium. This electric field goes from the n to ...
0
votes
1answer
2k views

PN Junction Depletion Region

So it took me a little bit to understand this, but I want to make sure I have a few things right. First of all, when a Crystal Structure with One side N-Doped, One Side P-Doped are in the same ...
0
votes
1answer
64 views

Regarding “Holes” in bands, and Photons

So from learning Band theory, and PN Junction and such, I've learned that photons are created when "holes" are filled in a band, and this is what can create light (Isn't this how LEDs work?) Anyways, ...
0
votes
1answer
76 views

Exciton energy splitting in indirect semiconductor

Let's take an indirect bulk semiconductor and imagine the exciton that build up at the indirect gap. Since we have a bulk semiconductor we should find three p-like orbitals: $p_x,p_y,p_z$. Would their ...
1
vote
1answer
110 views

Piezoelectricity in GaAs

I am studying the piezoelectricity in Gallium arsenide (GaAs), $[110]$ and $[\bar{1}10]$ oriented. Piezoelectricity is usually described microscopically by a 3 index tensor, $d_{ijk}$ where i,j and k ...
0
votes
2answers
2k views

Band Gap/Energy Bands in Semiconductors?

I think i've finally nailed down the Semiconductor Physics (Well the general part, whats and why's etc, as per my previous question) Anyways there is one small part that confuses me, and thats BAND ...
0
votes
1answer
622 views

Explanation for transistor as amplifier

In transistor as an amplifier, we have NPN transistor (base in the middle and emitter and collector at the sides). The collector has electrons in majority because it is N-type. similarly, holes are in ...
1
vote
1answer
542 views

Resistance of Light Dependent Resistor (LDR)

Is there a mathematical expression relating the resistance of Light Dependent Resistor (LDR) with light intensity?
1
vote
1answer
43 views

Looking for a reference book, or book chapter to learn about piezoelectricity

I'm looking for an introduction to the treatment of piezoelectricity, specially in semiconductors emphasizing the dependence on the orientation of the unit cell and the interactive effects with the ...
1
vote
2answers
302 views

Explanation of NMOS processes

Gate (poly-Si + $SiO_2$) and $p^{-}$ silicon operate as capacitors. But how are voltages and charges applied? In order for inversion to occur, there should be charges formed in poly-Si, right? How ...
2
votes
2answers
2k views

Mobility in semiconductors

Good afternoon everybody. I am reading on a book about semiconductor mobility. I have fully understood the definition, but I also noticed that often one talks about high or low mobility. My question ...
0
votes
1answer
2k views

Capacitance per unit area and CMOS case

In a modern 0.35μm CMOS processor, the gate oxide thickness is around 80Å = 8nm. This gives us a capacitance per unit area of $430nF/cm^2$ I am not getting how one gets this capacitance per unit ...
0
votes
2answers
364 views

The direction of electric field in a diode

Why electric field pointing to left? (The middle area is depletion region.) (This is without any external electrical voltage applied.)
0
votes
5answers
4k views

Current through the reverse biased junction in transistor [closed]

A transistor is a three terminal device. One terminal is called emitter, one collector and in between them is base. Now, during biasing the junction between emitter and base is made forward biased and ...
1
vote
1answer
232 views

Semiconductors and localization of the electrons

When looking at the band diagram of a semi-conductor, direct conclusion of the invariance under discrete translations, for a filled state with an electron, one does know precisely it's momentum, so my ...
2
votes
1answer
118 views

How creation of point defects in semiconductors is affected by strain?

When the effect of the strain on solids is discussed, normally the explanation is the following: increasing stress, first point defects created, then dislocations, then plastic deformation starts, ...
0
votes
1answer
103 views

Charge carrier injection in heterostructures - help with concept definition

I have this report to do on "Charge injection in heterostructures". I have been searching and reading but I still have some trouble with the basics, i.e. defining the concept. As far as I understood ...
0
votes
1answer
3k views

Characteristic of a common emitter transistor [closed]

How is Base emitter junction and collector emitter junction biased? How do we determine the value of potential difference between emitter and collector required to be maintained in order to determine ...
3
votes
1answer
285 views

Semiconductor problem: how much Boron is required to establish a certain amount of charge carrier density

The problem description is as follows: Boron is used to dope 1 kg of germanium (Ge). How much boron (B) is required to establish a charge carrier density of 3.091 x 10^17 / cm^3. One mole of ...
6
votes
1answer
821 views

How do Zener diodes maintain the potential across their terminals?

My physics book has a topic about Zener diodes being used as voltage regulators in the reverse bias. Well, I'm curious to know how does a Zener diode maintain the potential across its terminals after ...
1
vote
1answer
168 views

Metal rod between a capacitor

In my experiment, I am filling liquid crystal between two glass plates. Nn AC voltage is applied on them. The thickness of the liquid crystal cell is around $200 \mu m$. One glass plate is with +V and ...
0
votes
0answers
61 views

Quantum Mechanics Text for Electrical Engineers [duplicate]

Possible Duplicate: What is a good introductory book on quantum mechanics? What is a good introductory text on quantum mechanics that could be used to train electrical engineers in device ...
1
vote
1answer
344 views

Why do the drift and diffusion components cancel for each type of carrier if EHP generation plays such big role in p-n-junctions?

I have always argued to myself that drift and diffusion components of the current though a p-n-junction cancel for each type of carrier because any electron diffusing from n into p will sooner or ...
3
votes
1answer
152 views

Why does the Gallum-Arsenite bandgap narrow for higher temperatures and is this because of unavoidable impurities?

I found this sentence: GaAs at 300K contains 10^15 acceptor atoms per cubic centimeter. The bandgaps for Gallium Arsenite are: 0 Kelvin : 1.518 eV 300 Kelvin: 1.424 eV Now I am wondering: ...
2
votes
0answers
327 views

Solving a system of PDE equation in mathematica using a steady-state and time-evolution method [closed]

I'm working to solve the steady-state short circuit current of a solar cells, using the coupled continuity equations with a drift-diffusion expression and Poisson's equation: ...
1
vote
1answer
171 views

Reference for understanding characteristic length and time scales in a system (in particular electronic transport)

I am working on the transport properties of two dimensional electron gas in semiconductor heterostructures and am interested in the characteristic length and time scales of the system like elastic ...
1
vote
1answer
161 views

Why minibands are formed in superlattices?

In a single, finite quantum well, there are energy levels defined by the eigenstates - the solutions of the Schroedinger's Equation. The corresponding wavefunctions leak to the barrier because of its ...
5
votes
5answers
875 views

Derivation of Schrodinger equation for a system with position dependent effective mass

How to derive the Schrodinger equation for a system with position dependent effective mass? For example, I encountered this equation when I first studied semiconductor hetero-structures. All the books ...
2
votes
0answers
934 views

Why is the valence band maximum at the gamma point in the bandstructure view of dispersion relation?

Why is the valence band maximum for most semiconductors at the gamma point in the bandstructure view of dispersion relation
2
votes
1answer
192 views

Does anyone know the difference and relation between $k\cdot p$ method and tight binding (TB) method?

Among the methods of calculating energy bands for crystals, first-principles method is the most accurate. Besides first principles, two commonly used modeling methods are the $k\cdot p$ method and ...
2
votes
0answers
346 views

What is effective mass approximation

Currently i am studing about quantum confinement in semiconductors and came across effective mass approximation.but i am unable to understand this concept. what is the use of effective mass ...
2
votes
2answers
289 views

Problems in the modern semiconductor/electronics technology?

From what I have read, the problem with modern semiconductors/electronics seems to be quantum tunnelling and heat. The root of these problems is the size of the devices. The electrons are leaking out, ...
2
votes
2answers
2k views

Doping of pentavalent atom with hexavalent atom

We know that a tetra valent element can be a semiconductor and doping of pentavalent and trivalent impurities would give a extrinsic semiconductor. I got a question now. Can we use an element of ...
3
votes
4answers
2k views

(If and) Why does cold temperature affect semiconductors?

I had a college student build an overclocked PC using phase-change technology. (This is essentially an air-conditioning unit with the evaporator attached directly to the motherboard.) He said that ...
1
vote
4answers
2k views

Why does a semiconductor hole have a mass?

I have read that holes in semiconductor are nothing but vacancies created by electrons. But how can this vacancy i.e. hole has a mass?
3
votes
1answer
196 views

Confused about charge seperation in solar cells

I'm a bit confused about how solar cells work. My understanding is that there is a p-n junction. A photon is absorbed which creates an electron-hole pair, and the idea is to separate the electron ...
2
votes
1answer
1k views

What does the Fermi Energy really signify in a Semiconductor?

In understanding the behavior of semiconductors, I'm coming across a description of the Fermi Energy here and at Wikipedia's page (Fermi Energy, Fermi Level). If I understand correctly, the Fermi ...
2
votes
1answer
217 views

What is the difference between contact-limited and space-charge-limited charge transport?

I am reading a paper ("Tunable Electrical Conductivity of Individual Graphene Oxide Sheets Reduced at 'Low' Temperatures," Jung, et al. Nano Lett. 2008, 8, 4283-4287) about electrical conductivity in ...
3
votes
1answer
177 views

Theory of Space Charge in a Planar Diode

A planar diode in a vacuum bulb can support current in only one direction. To even get current flowing, you have to heat up the cathode filament to excite the electrons. However, once current is ...
2
votes
1answer
837 views

How is contact resistivity defined for a Schottky contact, or the Schottky barrier height for an ohmic contact?

Based on the transfer length method (TLM), one can accurately calculate the contact resistivity for an ohmic contact, by evaluating the absolute resistance measured through the test structure and ...
1
vote
2answers
172 views

Interpreting range of conductivity diagram

I have found the following diagram (unfortunately in german) about the range of conductivity of conductors (Leiter), semiconductors (Halbleiter) and insulators (Isolatoren). How should one interpret ...
4
votes
1answer
570 views

Turn-on delay time for Laser diode

Do you know any simple explanation on the reason why the turn-on delay time on a laser diode is reducing while we increase the bias current? Turn on delay,is the time that the laser needs from the ...
0
votes
1answer
628 views

Increase of threshold current by temperature in a laser diode

I read somewhere that if we increase the temperature of the material in a laser diode the threshold current for lasing also increases. Can someone explain to me why is this happening? What is the ...
1
vote
1answer
550 views

Physically what happens during Avalanche breakdown to the pn junction?

What does breakdown mean physically? I saw this in wikipedia: The avalanche process occurs when the carriers in the transition region are accelerated by the electric field to energies ...
1
vote
1answer
1k views

change of resistance in semiconductors due to temperature change

I have a question that popped up in an old exam I just can't find a way to solve. If you drop the temperature of this material from room temperature (I guess around 300K) to 0C (273K) the ...
0
votes
1answer
280 views

Equation for finding electrical resistance

I want to know how the flow of electrons will change when I change the tempertature from 100 F to 250 F in a silicon semi-conductor (ex: computer mouse) How can I find this out?