EFFECTS OF ANNEALING ATMOSPHERE AND TEMPERATURE ON ACCEPTOR ACTIVATION IN ZNSE-N GROWN BY PHOTOASSISTED MOVPE

Effects of annealing atmosphere and temperature on acceptor activation in nitrogen-doped ZnSe layers grown by photoassisted metalorganic vap or-phase epitaxy (MOVPE) have been investigated. It is shown that as-g rown high resistive layers are converted to p-type by thermal annealin g in N-2 atmosphere in the temperature range from 500 to 550 degrees C , while they do not if annealed in atmospheres of H-2, diethylzinc (DE Zn), and dimethylselenide (DMSe) in which hydrogen is contained. The n et acceptor concentration N-A-N-D has reached up to 4 X 10(17) cm(-3) by the thermal annealing at 500 degrees C, but it is lower when anneal ed at 550 degrees C. By exposing to H-2 atmosphere at 350 degrees C, N -A-N-D decreases with the exposure time. However, it almost recovers t o the value obtained by the first annealing in N-2, if the layer is an nealed again in N-2 atmosphere at 500 degrees C. These results are dis cussed based on the hydrogen passivation model, i.e. the dehydrogenati on and hydrogenation occur reversibly and result in activation and pas sivation of nitrogen accepters, respectively.