The effect of elastic strain on energy band gap and lattice parameter in III-V compounds

Abstract

The elastic and misfit strain in vapor-grown InGaP/GaAs crystals was determined by measuring the lattice parameter of the InGaP before and after removal of the GaAs substrate. The energy-band-gap shift as a function of strain was measured in a similar manner using photoluminescence. Up to 70% of the misfit strain was found to be accommodated elastically. The critical resolved shear stress for dislocation motion was found to be ∼2×109 dyn/cm2. The rather low band-gap shift with applied stress of ∼3×10−9 meV/dyn cm−2 was attributed to the Poisson effect. Photoluminescence was found to be a very accurate means to measure composition (and therefore lattice parameter), and empirical expressions were determined for the variation of photoluminescence wavelength with composition, lattice parameter, and energy band gap.