Raman Spectroscopy Study Of Polish-Induced Surface Strain In <100> And <111> GaAs and InP

Abstract

We report measurements of the first-order Raman spectra of the longitudinal optic phonon from the <100-> and <111> surface of GaAs and InP which have been polished by various procedures. Non-destructive depth profiling was accomplished by using different lines of an Ar+ laser. The observed lineshape changes have been quantitatively accounted for by a model based on the convolution of the penetration depth of the light and the skin depth of the polish-induced surface strain. For the <100`- surface we find the polish-induced surface strain to be compressive, fairly homogeneous and about 2-3% in both materials, relatively independent of particle size. The inhomogeneity of the surface strain in the polishing plane is less than 0.3%. The strain skin depth is substantially less than the particle size although it does increase with increasing size and polish time. For the <111> surface, although the surface strain is also compressive, the average surface strain is only about 0.6% for GaAs and 1.2% for InP. The inhomogeneous strain is about 1.4% in both materials. Also for this surface the damage skin depth is of order the particle size. For both surfaces we find that disorder is a minor effect for the grit sizes used and the dominant damage is plastic deformation.