Electroreflectance Studies of InAs, GaAs, and (Ga,In) As Alloys

Abstract

The technique of electroreflectance was applied to the study of epitaxial (Ga, In) As alloys. Two experimental methods were used and their relative merits are discussed. The ${\Gamma }_{15}-{\Gamma }_1$ and ${\Lambda }_3-{\Lambda }_1$ transitions and their spin-orbit splittings were investigated as functions of alloy composition. The spin-orbit splitting at $k=0\mathrm{}$ for InAs at room temperature was measured directly as 0.446±0.008 eV. The electroreflectance linewidth changes by a factor of 4 for the ${\Gamma }_{15}-{\Gamma }_1$ series between InAs and GaAs. The broadening is discussed in terms of mechanisms such as field inhomogeneity and light-hole lifetime for the InAs-rich alloys. The deviations from a linear concentration dependence that were observed for all of the energy gaps were almost all identical and were related to the virtual-crystal model. Transitions below the fundamental gap were correlated with impurities by the use of photoluminescence measurements on the same samples.