Questions tagged [semiconductor-physics]

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 harness it in electrical circuits.

Filter by
Sorted by
Tagged with
0
votes
1answer
56 views

How can electrons travel from the valence band into the conduction band?

I'm currently studying Introductory Semiconductor Device Physics by Parker. In band-theory, we know that if an electron is at the top of an energy band, then there are no allowed states immediately ...
1
vote
1answer
23 views

Why is silicon a good dopant for GaAs?

I have been looking into how GaAs and InGaAs quantum dots can be doped to make them negatively charged and I've found that they are doped will silicon. However, I'm struggling to understand why ...
1
vote
1answer
21 views

Does doped semiconductor have free electrons at 0K?

For intrinsic semiconductors, they don't have any free electrons at conduction band at 0k and behave like insulators. But if doped, let's say n-type doped, they will have extra electrons which do not ...
0
votes
1answer
30 views

Is semiconductor wafer neutral after ion implantation?

If ions are implanted in a silicon wafer as the term 'ion implantation' suggests, how can the wafer be electrically neutral after the semiconductor doping? Aren't the ions ions electrically charged? ...
0
votes
1answer
28 views

Figure Description of Equilibrium in a Crystal Lattice

I am reading an Introductory Semiconductor Physics by Parker. The textbook states the following: The ionic crystal itself is formed by the ions coming together in an equilibrium configuration. ...
3
votes
3answers
35 views

Photovoltaic cell as an instrument for measuring intensity of light

I teach a lab in which my students measure the transmission of light through polarizing films oriented at an angle with respect to one another. To measure the intensity of the light, we use a silicon ...
1
vote
0answers
29 views

Can anyone help me to clear some questions about diodes and transistors?

i don't understand the basic of the working of diodes, because i imagine that if we have a n-p junction and we want to pass current through from side of n region to p region, if we beat the potencial ...
0
votes
0answers
21 views

Why don't electrons build up opposite electric field in a semiconductor diode in open switch mode?

I understand that during the closed switch mode the opposite electric field gets wider, but i don't see the reason when in open switch mode when electrons beat the opposite p-n field (0,3-0,8 volts), ...
0
votes
0answers
24 views

Why Li is not added as contact by ion implantation method in p type HPGe detector? [duplicate]

n+ contact of p type Ge is ~700µm thick compared to p+ contact of n type Ge only ~0.3µm. The process of adding the contact is different. n+ contact Li is added by diffusion process but p+ contact B is ...
2
votes
3answers
62 views

An ohmic contact

It is claimed that Schottky type of contact between low work function p-type semiconductor and higher work function metal creates an ohmic contact in which current can flow both sides almost fluently ...
0
votes
1answer
40 views

Why do semiconductor lasers become weaker after extended use (not due to battery)?

Why do semiconductor lasers become less bright as they are used for longer periods of time (assuming their battery is full)? Does it have something to do with the PN junction reaching some kind of ...
-1
votes
1answer
106 views

Quantum tunneling in zener diodes

Well Zener diodes operate as a voltage regulator because of the Zener effect-Quantum tunneling . Quantum tunneling is the effect when an electron faces an energy barrier but after the energy barrier ...
0
votes
0answers
56 views

Why does the space charge in the depletion region in a pn-junction not create an electric field in the neutral region?

The majority carrier conduction electrons in the n-region of a pn-junction are closer to the the positively charged donor ions than the negatively charged acceptor ions in the p-region. The situation ...
0
votes
0answers
35 views

What is the density of states $SiO_2$?

We build the model by the finite element method. In our model here is silicon dioxide (SiO2). To carry out calculations, it is necessary to know the density of states and the effective mass. Question:...
1
vote
1answer
45 views

Under which condition the drift velocity stops increasing proportionally with respect to the electric field

Our professor asked us a question the other day but i wasn't able to figure it out. If we increasing Electric field then drift velocity will increase, Because of this Equation: Vd = μ * E But at ...
0
votes
0answers
38 views

Why and how do holes in the valence band of the p-type material of a p-n junction diffuse through to the valence band of the n-type material

tl;dr -- See the question title I quote from this Wikipedia article on the depletion region: By definition, the N-type semiconductor has an excess of free electrons (in the conduction band) ...
1
vote
1answer
37 views

Ion Implantation

I have a very basic question regarding ion plantation: when Silicon is doped with Boron, for example, it is doped by Boron atoms (3 valent electrons). When it is doped with phosphorus, for example, it ...
0
votes
0answers
10 views

Semiconductors with low thermal conductivity (lattice matched to GaAs)

What are the semiconductors with lowest thermal conductivity that can be grown on GaAs with the least possible incorporated strain (i.e. lattice-matched or close to it)? GaAs has thermal conductivity ...
0
votes
0answers
18 views

Can I consider electron scattering with grain boundaries in metal as a tunneling process?

I am reading about the Mayadas-Shatzkes model (MS model). when electrons are scattered with the grain boundary, there is a probability that it will be transmitted to the other side of the grain ...
0
votes
1answer
40 views

Quantum tunneling requirements

Why does quantum tunneling require a narrow potential barrier? I mean what makes zener diodes so unique is that they dont undergo heating because their potential barrier is very narrow.
0
votes
1answer
23 views

Electric fields and electric potentials in semiconductors

The zener diode is heavilier doped than a normal diode , that is why its depletion region is smaller than the delpetion region of a normal diode and that is why the electric field is very strong.Zener ...
0
votes
2answers
54 views

Why does the p-region have a higher energy level than the n-region in a diode?

Looking at the image below, I'm curious as to why the p-type region is at a higher energy level than the n-type region when no external voltage is applied. How is that? The E-field, if I'm not ...
0
votes
0answers
15 views

Zener diode electric field working principle

Well I recently saw a video from khan academy about zener diodes.This video was suggested by another member of Stack Exchange Physics who I thank him very much . But I didnt understand some things:...
1
vote
1answer
30 views

Chemical bond in diodes

Well I have seen diodes with many breakdown voltages. How is this possible ? I mean when an electron fills a boron hole it a bond is created between the boron atom and the nearby silicon atom.Well in ...
-1
votes
2answers
53 views

Will the electron-hole pairs in a solar cell ever run out?

I have read from various sources that, the photon strikes the solar cell and creates and electron hole pair which then migrates to their respective ends of the cells, this creates a potential ...
0
votes
0answers
21 views

Compensation Doping (Doping with 2+ elements)

In my microelectronics class we are talking about doping transistors. We learned how to calculate carrier concentrations for basic situations when we are doping a piece of silicon with one element. ...
0
votes
1answer
25 views

why in intrinsic semiconductor positive Silicon atom is known as hole but in extrinsic semiconductor positive Phosphorus is immobile ion? [closed]

why in intrinsic semiconductor positive Silicon atom is known as hole but in extrinsic semiconductor positive Phosphorus is not hole
2
votes
3answers
41 views

Why do electrons move towards a vacant position (hole) in a crystal lattice?

Why do electrons in a crystal lattice move towards the vacant position? Aren't electrons stable in their current position?
1
vote
3answers
57 views

Question about full wave bridge rectifier

Sorry if this is a stupid question, what I know is when a diode is forward biased, it conducts current, when it is reverse biased, it acts as an open branch if its $ PIV \geq V_{in}$ But in this ...
0
votes
0answers
19 views

Why does nMOS using N+ gate have lower Vth than nMOS using P+ gate ? (w/o band diagram)

I understand it from band diagram.(Band bending is more stiff in N+ gate case) However, I don't know what's essentially happening. If P+ gate and N+ gate have same dose, their poly depetion will be ...
0
votes
2answers
93 views

Difference between diode and LED

What is the difference between a diode and a led? I know a led is a diode and I know how they are used and so on but I'm not really sure why a regular is not also light emitting. Therefore, what is ...
1
vote
1answer
29 views

Resolve The Envelope Detector Circuit

I was working on a little project and I was wondering if the envelope detector circuit could be resolved analytically. Let me explain. The circuit is the one shown above, I know the values of $C$, $R$...
0
votes
0answers
30 views

Types of effective masses

I understand the existence of effective mass for electrons, light hole, heavy hole, and split-off. But how can they be different from the density of states effective mass of conduction and valence ...
0
votes
1answer
34 views

Gamma spectrometry: effect on one peak when adding another source

Suppose I have a sample containing only 137Cs. Now assume it shows 1000 cps counts for 137Cs, 662keV energy. Now I added 60Co (1173, 1332 keV) source in the same sample. Compton scattering ...
0
votes
0answers
27 views

Questions regarding germanium detector

Why n+ contact in n type Ge is not several hundred microns? . Why we require both additional p or n type contact? in p type Ge, why we require additional p type junction also? crystal itself should ...
0
votes
0answers
35 views

NPN transistors reverse biased

How is a pn reverse bias junction is formed in a NPN transistor? In a normal pn diode during a reverse bias junction an 'internal battery ' is formed which counteracts the movement of electrons . But ...
0
votes
1answer
40 views

In which region of diode breakdown starts?

i confused about in which region of a diode breakdown start, in some books it is given that breakdown starts in depletion region but in some other is said that it start in p-side or n-side of diode (...
0
votes
0answers
29 views

Splitting of energy levels in solids [duplicate]

when atoms are well seperated energy spectrum is discrete, but when they come together energy levels split and they form bands, upto this i can understand. where im confused is that these splitting ...
0
votes
0answers
16 views

What is a “space-charge”, in the context of photodetector non-linearities?

I'm going back and reading all these papers from a few decades ago regarding detector nonlinearities, and they talk a lot about space-charges and the space-charge field, but not one paper I've found ...
1
vote
1answer
69 views

Why n+ contact of p type Ge is 700um thick compared to p+ contact of n type Ge only 0.3um?

Whether the reason is as follows? Predominantly HPGe is p type. So compensation of large p type impurity requires more n+ contact. (700um) But n type Ge is made by doping of excess addition of n type ...
0
votes
0answers
37 views

Diffusion stopping current?

In the forward bias when electrons enter the p-type region of the semiconductor, the charge concentration is increased, and since the movement of electrons is faster than the movement of holes, it ...
-3
votes
1answer
55 views

PN Junction diode depletion width [closed]

depletion width formula of a pn junction diode has V(barrier)-V(external) i.e if the barrier potential is 0.6v(say) and i apply a forward voltage of 1V, then as per the calculation Width becomes ...
0
votes
0answers
17 views

on diffusion process in semiconductor devices

Consider a PN junction. Say that the P and the N sides are just brought into contact and the diffusion process has started. We say that as the diffusion occurs, the charge carriers leave behind ...
1
vote
2answers
79 views

Schrodinger equation in momentum representation with position-dependent effective mass

I'm trying to convert Schrodinger equation with position-dependent effective mass (PDEM) to momentum representation, and I'm not sure how to apply the kinetic energy operator. In position ...
1
vote
1answer
41 views

Quantum Mechanical Tunneling in a Resonant Tunneling Diode

I am currently trying to simulate a Resonant Tunneling Diode (RTD) on a somewhat basic level, so the question is rather general. Quantum-mechanically its structure is shown well in this figure: Two ...
0
votes
0answers
41 views

Chemical potential in a simple semiconductor

I came across the following problem in my undegrad solid state physics book: Assume a semiconductor with two bands, the lower band is defined as $E(k)$ and the upper band is defined by $E_0 - E(k)$ ...
4
votes
1answer
64 views

Semiconductors/insulators: Why is the fermi energy between the valence and conduction band?

Ive asking myself a question on the fermi-energy. The fermi-energy is defined as the maximum energy which an electron, following the Pauli-rule, can have at T=0. In semiconductors and insulators the ...
0
votes
0answers
33 views

Relation between intrinsic Fermi level and electric field

If I consider a semiconductor in equilibrium (type P or N, non uniformly doped, 1D situation), how can I express the electric field in terms of the intrinsic Fermi level? I am trying to approach this ...
0
votes
0answers
30 views

Working of a photodiode

I am reading photo diode and I have couple of questions in. So my understanding of a photodiode is that these are devices which consume electricity and produce light So if that being the case, I am ...
2
votes
2answers
89 views

Why can blue LEDs be used for generating white light, but red LEDs cannot

LEDs consist of pn-junctions, so why can blue LEDs be used for generating white light, but red LEDs cannot