Characterization of Nitrogen-Doped ZnSe and ZnS0.06Se0.94 Films Grown by Metal-Organic Vapor-Phase Epitaxy

The relations of doped nitrogen (N) and deep-level emissions such as Y lines (477 nm) and self-activated (SA) emissions (∼580 nm) were investigated in detail by photoluminescence measurements mainly in ZnS0.06Se0.94 films lattice-matched to GaAs. The Y and SA emissions in the N-doped ZnS0.06Se0.94 films both showed appearance of a `threshold' for the incident optical power, indicating the existence of the activation energy on these lines. Persistent photoconductivity was observed for the first time in the N-doped ZnS0.06Se0.94 films which corresponds with the above new finding. The electrical property of the lattice-matched ZnS0.06Se0.94 film was p-type with a carrier concentration of 7×1015 cm-3 which is the highest carrier concentration ever reported with N-doping, while the lattice-mismatched ZnSe film was highly resistive. It was pointed out that the partial incorporation of the doped N-into the defect sites related to the Y line is still compensating the p-type property, even in the lattice-matched films.