Effect of Indentation Load on Raman Spectra of the InP Crystal

In this study, the Raman spectroscopy method was used for examination of structural changes made on the (001) surface of InP crystal using nanoindentation with a maximum load up to 100 mN. The presence of the metallic, high-pressure B1 phase of InP was not confirmed. Consequently, this result indicates a dislocation-governed mechanism of nanoindentation induced incipient plasticity of InP crystal. An increase in the maximum load caused a decrease in the width as well as a shift in the main Raman bands (LO, TO) into lower frequencies. Our findings were explained under assumption that an increase in the maximum load causes a decrease in both the dislocation density and the stresses in the vicinity of residual impressions. This unexpected relationship was confirmed by results of nanoindentation experiments.