Recent content by zhanghe

Thanks guys. I could withdraw this "problem" for now. Finally, I found my mistake, the bipolar transport, ie. the movement of the delta n is totally different the electrical current. the bipolar is more like a kind of forms, but when you look into the current, you have to go to the movement of...

When there is a current in a material externally biased, could you help me to analyze the composition of the current, the density of two carriers and their movement direct? I thought about it for a while last night and attach a file below, that could explain my confusion easily.

There should also be a photocurrent on a p-type (or n-type) material without PN junction, the so-called the light-conductivity for material. :confused:

I feel quite confused for a few days, when I apply the bipolar transport equation into a voltage-applied semicondutor material (e.g. p-type c-Si bar, or a resistor) which just have some light-generated electron-hole pairs by a pulse of photon at somewhere on the bar. In terms of bipolar...

Well, the m* of hole is positive.

When a transition happens that an electron jumps from VB to CB by being excited only by a photon, the electron always jumps almost vertically in the E-k diagram. The momentum conversation is still held though the election velocity direction becomes reverse. But do not forget that its effective...

First of all, you must be aware of that the built-in voltage is the one that is defined between the two edge of the depletion region, we do not care about other parts of pn-junction in our textbook for simplicity. When you have to consider bias voltage, in practice, two semiconductor-metal...

Dear hokhani, Remember we used the periodic boundary condition, just because we have decided to ignorate the effect of the boundary, so you of course can not get any results about "travelling beyond end points". Anyway, in most semiconductor textbook when we consider interaction btw. phonon...

When electron is excited from valence band to conduction band, i do not think we should try to understand the mechanism using classical picture, though quasi classical mechanics is applied widely in semiconductor but only limited in same band, I think. let us go to quantum physics, outside the...

dear DrDu, so you mean, standing or traveling depends on the condition?

The superconductor with the highest transition temperature that has been confirmed by more than one independent research groups (a prerequisite to be called a discovery) is mercury barium calcium copper oxide (HgBa2Ca2Cu3O8) at around 133 K. "From wiki :)"...

I agree with you that these 5 phonons strengthen 5 times the effect of one of them.

in my opinion, traveling wave, because hear (as energy) could be transported from hot part to cold part by phonon.

which kind of velocity are you talking about, phase velocity (k) or group velocity (dE/hdk)? different velocity, different answer.

1 far away enough that they do not affect each other, that is why we regard them as two alone systems. 2 "splitting" is referring to the energy, 3 of course different as the picture implies due to Pauli's exclusion principle,