Vibrational spectroscopy of arsenic-hydrogen complexes in ZnSe

Abstract

Using infrared absorption spectroscopy, we have observed hydrogen local vibrational modes (LVMs) in arsenic-doped ZnSe grown by metalorganic chemical vapor deposition (MOCVD). When hydrogen is used as a carrier gas, we find an absorption peak at 2165.6 cm-1, which we attribute to a bond-stretching mode of a hydrogen attached to an arsenic acceptor in a bond-centered orientation. With deuterium substituting the hydrogen carrier gas, we find an additional peak at 1557.1 cm-1 with 1/3 the intensity of the hydrogen peak. The isotopic frequency ratio is r=vH/vD=1.3908, similar to values found in many hydrogen/deuterium-related complexes. The larger area of the hydrogen peak indicates that most of the hydrogen comes from decomposition reactions involving the metalorganic molecules. The temperature dependent shift of the ZnSe:As,H mode is proportional to the lattice thermal energy U(T), a consequence of the anharmonic coupling between the LVMs and the lattice phonons.