Electronic Structures of GaAs-Ga1−xAlxAsRepeated Monolayer Heterostructure

We present the first pseudopotential calculation of the fundamental band gaps for heterostructures consisting of alternating monolayers of GaAs and ${\mathrm{Ga}}_{1-x}{\mathrm{Al}}_x\mathrm{As}$ ($0<~x<~1$). Significant differences are found between the GaAs-AlAs gaps and those of the ${\mathrm{Ga}}_{0.5}$ ${\mathrm{Al}}_{0.5}$As random alloy. The imaginary part of the dielectric function has been calculated for GaAs-AlAs and appears consistent with the experimentally reported optical absorption edge.