Recent content by scivet

The epsilon is positive at the higher frequency than plasma, which means the transverse propagating wave. Right? So, epsilon is zero, then the electromagnetic wave equation says del^2 E is zero. How does this say the solution is longitudinal? It only says K, the wave vector must be also zero?

Kittel solid state physics book ( chapter 14)says when dielectric permittivity is zero, then longitudinal polarization wave possibly exists. It is hard to imagine how this is possible. Can anybody explain this? If the permittivity is zero, then there shouldn'n be any response, right? How come...

Thank you so much guys. All the replies were really helpful.

So, if we consider only linear conductivity of Si, then it must be isotropic. But in reality, the conductivity of Si is not linear and it would have higher order (greater than 2) rank tensor properties. The origion of anisotropic conductivity of Si comes from non-linear conductivity, not from...

The crystal system of diamond is classified into cubic (Refer to Nye's book, "Physical properties of crystals", page 107, the 1985 edition, section thermal expansion coefficient). In his book, Nye says diamond has isotropic thermal expansion coefficients (Chapter VI, table 6). The thermal...

All the FCC lattices have the most densel packed planes on [1,1,1]. Is the anisotropic ethcing rate related to the diamond structure rather than the FCC structure?

Thank you for the answers. tejas, you said Si is not a cubic. But the wikipedia says, "Diamond cubic is in the Fd3m space group, which follows the face-centered cubic bravais lattice.". So is SI really not a cubic? I think the Diamond is not a Bravais lattice but we can convert it to the...

As I know, electrical conductivity is a second rank tensor. So in a cubic structure, there is no orientation dependence of electrical conductivity (isotropic). But how come Si has higher electron conducitivity along [001] and hole conductivity along [110]?

I'm wondering what determines Si indirect semiconductor? Si is cubic diamond structure. So it's optically and electrically isotropic (1st&2nd rank tensor properties). And why is GaAs direct semiconducto even though its crystal structer and chemical bonding is so simliar to Si? Isn't it crystal...

light speed in the media = c/n