High-Pressure Studies of Absorption and Luminescence Spectra in 3C-SiC

Abstract

The pressure dependence of absorption spectra in 3C-SiC crystals has been studied up to 14 GPa at room temperature by using a diamond anvil cell. The pressure derivative of the fundamental gap between Γ_v and X_c band extrema is found to be −1.9 meV/GPa, the absolute value of which is anomalously small, in contrast with the values usually observed for Γ_v−X_c (or Δ_c) gaps in the diamond and zinc-blende structure semiconductors or insulators. Luminscence spectra measured at 1.8 K reveal that the binding energy of excitons trapped by donors increases drastically at pressures higher than 4 GPa.