Acceptor–hydrogen complexes in semiconductors under pressure

Abstract

The structure of acceptor–hydrogen complexes is a subject of fundamental and technological interest. To probe the interactions between hydrogen, the acceptor, and the surrounding host atoms, hydrostatic pressure may be applied over a wide range. Using infrared spectroscopy at liquid-helium temperatures, we have observed carbon and carbon–hydrogen local vibrational mode (LVMs) in InP at hydrostatic pressures as high as 5.5 GPa. For pressures beyond 4.5 GPa, the carbon–hydrogen mode was not observed, perhaps as a result of a transformation of the complex into a different configuration. The LVM arising from carbon substitutional impurities varies linearly with pressure, whereas the shift of the carbon–hydrogen mode has a positive curvature. Both of these observations are in qualitative agreement with the pressure dependence of LVMs in GaAs. While the substitutional carbon impurities show very similar pressure shifts in the two materials, the linear pressure coefficient of the carbon–hydrogen stretch mode in InP is nearly three times that in GaAs.