Semiconductor Definition and 347 Threads

Homework Statement A certain doped semiconductor at room temperature has the following properties: no = 9 x 1014 / cm3, po = 4 x 1014 / cm3, μe = 800 cm2 / V-s, μh = 400 cm2 / V-s, and (Dh\tauh)1/2 = 10-4 cm. If an electric field is applied, what fraction of the resulting drift current flow...

Suppose there is a semiconductor with Fermi energy $E_f$ and that there are $N$ bound electron states. I'd like to know why the mean number of excited electrons takes the form \bar n(T)={N\over \exp\beta(\mu-E_f)+1} where \mu is the chemical potential. ____ I can see that the Fermi...

Why n*p always equal to ni square?? (semiconductor) Hi, For you guys who studied semiconductor physics must be familiar with the equation: np=ni2 I can understand why this is true for the intrinsic case (the broken bonds would always provide electron and hole in pairs ) But why is this...

Hi! I study semiconductors and I am confused with the bonding picture for semiconductor crystals. For example, it is said that in Si crystal one can find covalent bonds. In the most books this bonds are shown like that: 2D crystal structure where lines between atoms are a covalent bonds, each...

Homework Statement rho(x) = 0 for x >= Xo and x <= -Xo rho(x) = ρ1 for 0< x < Xo rho(x) = -ρ1 for -Xo < x < 0. The last two rho's are constants. Electric field = 0 for x> Xo and x < -Xo. Find E for -Xo< x < Xo Homework Equations I used the ∇. E = ρ / epsilon The Attempt at a Solution...

Homework Statement The drift current in a p-n junction is 20μA . Estimate the number of electrons crossing a cross section per second in the depletion region. Homework Equations Drift current is the current that occurs due to formation of holes and electrons in the depleted region from...

why p type semiconductor is electrically neutral and what is the concept of drift current?

Can a hole go to conduction band? In p-type, the hole is above the fermi level, lower than conduction band, higher than valence band, how can this be happened? And will this happen when the p-type is at 0K

Please I need help to understand how diffusion current can occur in a circuit that contains an N-type or P-type semiconductor without being connected to an electric souce such as a battery.And how can both drift and diffusion current occur when the circuit is connected to a battery?

In intrinsic semiconductor, electrons jump into conduction band, a hole is left in valence band. My question is the above statement correct? I though the hole is something we imagine, how to say the hole is in the valence band? If I said an electron is in valence band, is that implying that...

Hi all, when we shine light on semiconductor surface with white light, superband gap transition occurs (VB to CB). Also we have surface state (SS) too, so there is probability of transition from VB to SS and SS to CB as well. The time transient of this surface is similar to charging of a...

Hi, I have a question regarding the change in charge carrier concentration change. For a given semiconductor, say Silicon, when it is not doped, it is easy to understand that {n_0} \times {p_0} = n_i^2, however, on doping with donors to form a n-type semiconductor, we have {n_0} \approx...

Look at the picture... Here current is flowing through a semiconductor... First think about holes... The holes will pile up on the upside... But if you think about electrons then the electrons also pile up on the upside... What's wrong here? Is it wrong because it is more appropriate to...

This question is about seebeck effect. If the movement of hole(positive charge) happens because of electrons moving in opposite direction, how is the heat carried by hole when one side of p-type semiconductor is heated? Is it from lattice vibration?

Homework Statement Determine the total number of energy states in silicon from the edge of the conduction band to Ec + kT for T = 300K. Homework Equations N = \intg(E)dE The Attempt at a Solution I'm pretty sure I know how to do this one. The only problem is, when I get to the...

Can anybody explain... what makes silicon indirect band semiconductor? thanks in advance Vani

Dear physics forums users, I'm reading a paper saying "For hole density p\sim 10^{17} - 10^{18}/cm^3, the screening length in silicon, \lambda_{Si}, is ~1-2nm." For this, the paper references Sze's, Physics of Semiconductor Devices. I'm unable to find the formula by which the authors seem to...

Hi, I just read a paper about charge transport in organic semiconductor. There, it was mention that from electrochemical experiments, it is well known that after the removal of one electron from an individual molecule, more energy is required to remove a second electron. I'm still confuse...

I would like to have at least a vague idea how coherent is light from an inexpensive 1 mW red semiconductor laser which I have. I tried to find the manufacturer using Google, but I haven't found it. I would like to know the coherence length and the degree of spatial coherence. Is there...

Hi everyone, I have a question here on what cause doped semiconductors to conduct. (such as Silicon with some As present, this is one atomic number higher) On my chemistry book, it says As covalently bond with 4 Si atoms as Si does, so the lattice is preserved, and 1 of its valence electron is...

Semiconductor dioedes ! when proving that the ideal diode is short circuit in forward biasing we calculate the diode Resistance Rf which is equal to the diode forward voltage upon it's forward current ...but why we put VD=0 why?

Right, so I'm a freshman in college right now, so if I'm wrong, I'm wrong. Would it be possible to get a biological system to imitate or act like a semiconductor or nanoelectronic device or is that a fantasy? Does anyone here have experience doing it? Or perhaps use nanoelectronics to solve...

Hello. "Hypothetically" let's say that I have a material that intrinsically behaves like a highly degenerate p-type direct gap semiconductor (significant p-orbital contribution to the DOS at and above the fermi level). Can anyone think of what in the world such a material may be useful for...

In a semiconductor @ 0k highest energy state lie on fermilevel(all electrons @ valence band). but @ room temperature highest energy state of covelence band lie below the fermilevel. how can i understand this? pls help me.

THE TEMPERATURE DEPENDENCE OF THE ENERGY GAPS IN SEMICONDUCTORS Where I can find text about this topic and models that describe this? I know about Linear and Varshni models, and what about two (or more) other models?

i have a general question that I need to know to apply for jobs. What do we mean by "semiconductor industry"? and where is most of the semiconductor industry located? I know Silicon valley but according to my survery most of the industry there is like google, youtube, facebook etc.

I've been having a very difficult time understanding why band structure is expressed in terms of momentum/crystalline directions. I've included a picture of the band structure of silicon so that you can better understand my question. I think I understand basic crystalline structures and the...

I'm extremely interested in semiconductor devices (MOSFETs, BJTs, diodes, etc) and I plan on pursuing a career in this field. However, what I am contemplating is whether or not it would be beneficial to pursue a masters before attempting to get into the semiconductor industry, or if a BE is...

Are the electrons in the donor and recipient energy bands in doped material involved in conduction of electricity, and why?

Will a current through the ptype + metal material be very low because of the ptype material? Does a junction like a pn junction form between the ptype semiconductor and the metal? Thanks for your time.

Hello All; This is a question I found in semiconductors and devices by Kanaan Kano. Basically, the volume of a bar of Silicon is given at 300 K [1x0.01x0.2 cm]. How would you find the resistance of the bar if it is intrinsic. Also, what will be the new resistance after doping of 10^15...

Homework Statement A semiconductor diode is made of acceptor and donor dotted regions. In equilibrilum there is a volume charge region at about x = 0. In that region there is no free charge carriers, only single charged. In x<-dp and x > dn, there is no charge at all. The surface area of the...

Or is 'semiconductor' more specific, referring to only some transition metals? After looking up the etymology*, I guess that a hypothetical material besides the transition elements which had properties which met the definition of 'semiconductor' would qualify; but that doesn't completely...

Many of you may be annoyed by my question. I'm sorry in advance. I've just finished my M.S. in Materials Science & Engineering, and have gotten an offer as a Semiconductor Process Engineer. The specialty is lithography and wet chemistry - including wet etching. As an MSE student I learned...

Greetings, Could anyone help to tell me how to estimate the dielectric constant of cobalt oxide? Cause I have looked for the database, and couldn't find the data. Very thanks, jovis

Greetings everyone. A little about my situation: I'm a 3rd year student studying in New Zealand, specialising in a 4-year undergrade program on optoelectronics, basically a mixture of computer systems engineering, electrical engineering, physics papers on optics and electronics. On my...

We know that the built in potential barrier Vb does not allow any net current in a semiconductor. Now when we connect a battery in forward biased with the voltage V the current begins to flow even if V<Vb. Agreed. But my text says that V cannot exceed Vb is this true? for reference...

When we provide thermally or optically en energy higher than the semiconductor bandgap we create elctron-hole pairs, that is electrons are extracted to the valance band and they become free to move inside the crystal. My question is: are the semiconductor atoms then ionized, which means for...

Hiya, been given this question which I am having problems with. Semi conductor quantum well structure contains a 100A thick layer of GaAs between thick AlGaAs layers. Find the band gap for the structure, where GaAs has the following parameters; conduction band effective mass 0.067 me, heavy...

Hi, I am from an engineering background and I am in the process of learning about semiconductor physics to get a more generalized picture on the operation of the devices rather than just the operating characteristics. To start with I am studying about the p-type and n-type semiconductors...

Hi just a quick question, does the type of impurity (as long as its from group 3 or 5 respectively) used in doping a semiconductor matter in terms of its activation voltage or is it just down to the level of doping? So for instance a would say a silicon semiconductor doped with 1 to 10,000...

Hi all, I'm a math major about to take the plunge into EE in hopes to work in the semiconductor industry (hopefully working on CPUs, GPUs, etc.). I have math degree, so mathematically challenging aspects of things don't scare me too much. However, I have a question about how working in the...

Hi everyone, :smile: I was wondering why they only use 5th and 3rd groups elements to create n-type and p-type semiconductors respectively. Couldn't we mix 6th or 2nd groups' elements instead to make the semiconductors? What would happen if we do this? Perhaps elements of those groups will...

Hey guys, since this seems to be the brainiest place on the web for physics and engineering topics, I was wondering if you guys can help me out. I have to do a short encyclopedia page for my semi-conductor class about sensor applications. Now, after doing a little bit of research, I thought...

Hi, I have a question regarding Energy band. The energy band of a simple cubic semiconductor crystal with a lattice constant b can be represented as in the following function: E(k) = E0 + E1[cos(kxb) + cos(kyb) +cos(kzb)] where E0 and E1 are independent of the wave vector k. i)...

what is the difference between a commercial grade IC and an Industrial grade IC. Industrial works at a wider temperature range. I am not asking about that. What is it that you change inside the chip that makes it work at higher temperature ranges?

for the semiconductor which doping both donor and acceptor impurities... for example,determine the hole and electron density thermal equlibrium densities and the location of fermi level with respect to Ec,for a silicon at 300K that is doped with 3x10^6 boron and 2.9x 10^6 phospohorus...the...

I have been told that the relationship n.p = (n_i)^2 always holds, where n_i is the intrinsic carrier concentration. This makes sense to me for an un doped semiconductor (sc.). However, for a doped sc., I'm a tad confused. For an n-doped material say, the electron conc. is...

I just finished reading Absolutely Small, a book on quantum physics. In it the author says that when semiconductors get very cold the electrons no longer have enough energy to jump the band gap, and therefor they do not work. I have also watched a video of a guy who poured liquid nitrogen...

Over the past 3 months I've been watching Leonard Susskind's lectures (Stanford) on quantum mechanics and particle physics from YouTube. This has been an enjoyable experience and I would like to further my own education. My interest is in semiconductor physics particularly modelling using the...