Chapter 8-1

Ge Si

ħ << Eg

(T = 0)

Vertical transition

Direct Transition Indirect Transition

ħ << Eg

Optical absorption to determine the (direct) energy gap of InSb

Direct Transition at 0.23V

OF AN ELECTRON IN AN ENERGY BAND

Without interaction with the crystal potential

With interaction with the crystal potential

Then, summation over all possible G

for a given G

is