# Tag Info

## Hot answers tagged semiconductor-physics

20

As you have expected, there is no sharp divide between the groups. The divide is man made. Since all conductors have some resistance, (except superconductors - follow this link to find out more) and all insulators will conduct some current if they are forced to, this means there is no absolute dividing line between conductors and insulators. Since ...

8

Another way of distinguishing conductors and non-conductors or insulators is with band gap - for good conductors the fermi level of electrons is inside a band - semiconductors have a small band gap and good insulators have large band gaps... Electrons in solids lie in energy bands, whereas in atoms and molecules they have generally sharp levels. If you ...

2

If you take a diode that isn't connected to anything we get the usual depletion layer at the PN junction: And we get a potential difference generated across the junction. Suppose we now connect the two side of the diode with an external wire, then a second depletion zone develops at the connections with the wire: And this depletion zone has a potential ...

2

Sometimes word usage is well-standardized, for example the words work and heat are well defined. Sometimes it is not, and one must be careful to understand what is meant by context. I don't believe that Schottky Barrier is as well standardized as work, but I think it's usage leans strongly toward the classic metal/semiconductor interface. I suppose it ...

2

Electrons and holes occupy their states according to the Fermi-Dirac distribution, which has a single parameter $E_f$, the Fermi level (assume a fixed temperature). Provided $E_f$ is in within the band gap and far from the band edges, the (energy integral of) Fermi-Dirac takes an exponential form $\propto e^{E_f}$ for electrons and $\propto e^{-E_f}$ for ...

1

What happens when you touch an object with a positively charged object? Ans: It gets positively charged. Now, you have connected a semiconductor to a positive end of battery. What do you expect? Ans: Yes, it gets positively charged. Will the terminal pull electrons out of the doped silicon, or equivalently, inject holes into it? Yes, it will. ...

1

If you inject electrons in the p-type material, they will "immediately" recombine with holes there (which are in excess). If you inject holes in the n-type, conduction electrons (which are in excess) will "immediately" fill them. As stated by Jon Custer, if you create electron-hole pairs in the depletion region, the field will separate them, thus creating a ...

1

Ultrashort pulses impinging a semiconductor usually generate some level of THz radiation. Electron-hole pairs in a free standing semiconductor can be generated by resonant absorption or by two-photon absorption, depending on the wavelength. They create a transient radiating dipole through the photo-Dember effect. If lacking central symmetry, the ...

1

A compositional superlattice is a periodic layer structure of different materials. These typically have different bandgaps, effective masses, refractive indices etc. There are limitations on which materials can be stacked. They need to have the same crystal structure and lattice constant or at least negligible strain. The model system would be $GaAs$/$AlAs$ ...

1

The way mobility depends on average scattering time of the carriers is given here: A simple model gives the approximate relation between scattering time (average time between scattering events) and mobility. It is assumed that after each scattering event, the carrier's motion is randomized, so it has zero average velocity. After that, it accelerates ...

1

An empirical answer: Metals (often copper) can be used as insulating support structures in superconducting magnets. Compared to ~0 resistivity of the coil, the resistivity of metals makes for very good insulating properties! Or, going in the other direction, a 50-watt VandeGraaff-type power supply may output 500KV at 100uA. Such a supply has an internal ...

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