The effect of lattice mismatch on the properties of In1-xGaxAs/InP heterojunctions

Abstract

The effects of lattice mismatch normal to the wafer surface between In1-xGaxAs layer and InP substrate on structural, electrical and optical properties have been examined. The In1-xGaxAs epitaxial layers were grown on (100) InP substrates by liquid-phase epitaxy using the step cooling technique. The mobility of the epitaxial layers is apparently reduced with increasing lattice mismatch. The measured room temperature carrier concentration and mobility of the lattice-matched In0.53Ga0.47As layer were 8×1015 cm-3 and 8300 cm2/V·s, respectively. The peak wavelength, intensity, and the full width at half maximum of the photoluminescent spectrum measured at 16 K are also dependent on the lattice mismatch. It shows that the narrowest full width at half maximum of the photoluminescent peak of the lattice-matched wafers is 8 meV. Because of the formation of strain or misfit dislocations in the lattice-mismatched heterojunctions, the disorder activated longitudinal acoustic mode of the Raman scattering spectrum and the broadening parameter of electrolyte electroreflectance spectrum are also greatly influenced. It shows that the minimum broadening parameter in electrolyte electroreflectance measurements is 30 meV at the lattice-matched condition. © 1989.