The variation of residual impurities in ZnSe crystals used in light-emitting diode fabrications

Recent reports in the literature suggest that residual impurities, probably interstitial lithium, are responsible for the strong compensation of p-type conductivity in ZnSe. Data presented here support these findings. ZnSe boules that had high Li content, as determined from the pair band of the emission spectra, produced poor light-emitting diodes (LED’s). At the same time LED’s were consistently good when boules that contained less residual Li were used. Ion microprobe measurements showed that one of the processes that takes place during LED fabrication is the reduction of the residual Li content. These two findings together show that low Li content is a prerequisite for good LED formation.