Effect of growth conditions, surface orientation, and alloy composition on Cl incorporation and activation in ZnSe and Zn1−xMgxSe grown by molecular beam epitaxy

While chlorine can be incorporated in ZnSe at levels up to about 2×1020cm−3, it is only electrically active at levels up to 1×1019cm−3 with almost complete compensation occurring beyond this point. The doping level at which this compensation occurs coincides with a dramatic decrease in growth rate when using ZnCl2 as the chlorine source during growth by molecular beam epitaxy. The decrease in growth rate is likely due to competition for Zn atoms between growth and the chlorine. Compensation and degradation of photoluminescence edge emission intensity appear to be directly correlated to the reduced growth rate. Surface chemistry effects on point defect formation and surface reaction kinetics are investigated through comparison of growth and Cl doping of ZnSe on (100) and (211)B oriented substrates, and by dramatically modifying Zn-to-Se ratios during growth. It is shown that growth conditions can be modified to overcome Cl-related growth rate reduction, recovering to some extent the optical and electrical ...