Conduction mechanism in low-resistivity n-type ZnSe prepared by organometallic chemical vapor deposition

Abstract

n-type ZnSe layers with a room-temperature resistivity of less than 0.05 Ω cm and mobilities of ∼400 cm2/(V sec) have been grown on (100) GaAs by organometallic chemical vapor deposition (OM-CVD), using triethylaluminum as a dopant. No further treatment after the layer growth is necessary in order to achieve the high electrical conductivity. An analysis of the low-temperature electrical transport data and of the photoluminescence data, however, suggests that the physical properties of the layers differ from those of ZnSe prepared by other methods. Charge transport occurs via impurity-band conduction in the more heavily doped layers and via thermally activated hopping in the more lightly doped layers rather than via thermally activated extrinsic conductivity. The degree of compensation of donors is larger than 0.5. The exact nature of the compensating centers in the material prepared by OM-CVD is uncertain at this point, although the photoluminescence data suggest the presence of Al-VZn complexes.