Question

What are direct and indirect band gap semiconductors???

Answer 1

Answer:For the direct band gap material, you have to plot (αhv)2 vs. hv (energy in eV). Where, α is absorption coefficient (cm-1), hv is energy in eV. Then, the direct band gap energy, Eg, can be obtained by extrapolating the linear portion to (αhv)2 = 0 in that graph.

For the indirect band gap material, you have to plot (αhv)1/2 vs. hv (energy in eV). Where, α is absorption coefficient (cm-1), hv is energy in eV. Then, the indirect band gap energy, Eg, can be obtained by extrapolating the linear portion to (αhv)1/2 = 0 in that graph.