Photoreflectance study of crystalline silicon

Photoreflectance study has been performed to determine the E0′, E1 and E2 critical-point (CP) energies in crystalline silicon at temperatures T between 77 and 300 K using an Ar+-ion laser as the modulation light source. The measured photoreflectance spectra have been successfully explained by a standard CP line shape. The temperature dependence of the E0′, E1 and E2 CP parameters (band-gap energy, amplitude and broadening parameter) has been analyzed using the Varshni equation and an empirical expression of Bose–Einstein type.