Strain gradients along the growth direction in thin diamond film deposited on silicon wafer

摘要

A strain gradient has been observed along the growth direction of 5 μm thick diamond films, grown on silicon wafers. On detachment, films were found to adopt curvature such that the free surfaces became concave which indicates residual stresses which are compressive near the interface and tensile near the free surface. Raman peak positions were found to shift upward near the interface and downward near the growth surface. Raman spectra from the interface showed higher level of sp~(2) hybridized carbon. The quality of the diamond was found to improve as the film thickness increased. Luminescence spectra were also examined to study the variation in defect density across the film thickness and its possible contribution to the observed strain gradient.