Thermal annealing and zinc doping effects on the lattice constant of organometallic vapor phase grown GaAs epilayers on heavily In-doped substrates

Abstract

Undoped and Zn-doped (∼3×1020/cm3) GaAs epilayers are grown on In-doped (order of 1020/cm3) GaAs substrates by the organometallic vapor phase epitaxy method. By thermal annealing of the undoped epilayer, changes in the perpendicular lattice constant a⊥, together with the apparent changes in surface morphology such as the appearance of a cross-hatched structure or a narrowing of the cross-hatched line spacing, are observed. It is also found that Zn doping is very effective to obtain thick, coherently grown epilayers on In-doped GaAs substrates. No appreciable changes in a⊥ and no generation of misfit dislocations are found because of the hardening of the crystalline lattice, similar to the case of In doping to GaAs bulk crystals.