Influence of growth temperature on stoichiometry in ZnSe

Abstract

The influence of growth conditions such as substrate temperature Ts and [H2Se]/[dimethylzinc] ratio on the electrical and luminescence properties has been investigated for undoped ZnSe films grown on GaAs(100) substrates by metalorganic chemical vapor deposition. The observed electrical and luminescence properties are consistent with each other and depend on the deviation from stoichiometry. The properties of the films and the solubility of NSe using N2 gas confirm that at Ts ≤350 °C the deviation from stoichiometry depends on the VI/II ratio. In contrast, it has been difficult to prepare Zn-rich films at Ts ≥375 °C. The VI/II ratio necessary for preparing stoichiometric films decreases rapidly with increasing Ts . The film with the highest mobility maximum of 7600 cm2/V s at ∼40 K has been grown by controlling the stoichiometry. The concentration of acceptors incorporated during growth is lowest in stoichiometric films. It is suggested that the extended lattice defects which reduce the electron mobility are formed more easily as the composition changes from Zn rich to Se rich. The reduction in the deviation from stoichiometry on the Se-rich side is the most important for obtaining low-resistivity n-type ZnSe. The results are consistent with the reported results for bulk crystals.