Post growth n-type doping of ZnSe-bulk single crystals

In this paper we show that the reproducibility of carrier concentration aft er annealing treatment of ZnSe strongly depends on the state of the origina l crystals, i.e, their content of residual impurities. Different charges of the ZnSe crystals were investigated by glow discharge mass spectrometry (G DMS), photoluminescence and Hall-effect measurements before and after an an nealing treatment in molten Zn (100 h at up to 950 degrees C). These measur ements reveal a purification concerning the highly mobile acceptor impuriti es Li and Na and a dependence between the measured carrier concentration an d the net donor impurity concentration (In, Al, Cl ... max. 5 x 10(17) cm(- 3)). In this consequence, we doped high purity vapour grown ZnSe samples in tentionally by adding ZnCl2, In or Al to the Zn melt. The interdiffusion of Al was found to be the most efficient way of post growth n-type doping. Ca rrier concentrations of up to 10(18) cm(-3) were obtained. (C) 1999 Elsevie r Science B.V. All rights reserved.