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 vapor-phase epitaxy (MOVPE) have been investigated. It is shown that as-grown high resistive layers are converted to p-type by thermal annealing 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 (DEZn), and dimethylselenide (DMSe) in which hydrogen is contained. The net 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 annealed 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 to the value obtained by the first annealing in N-2, if the layer is annealed again in N-2 atmosphere at 500 degrees C. These results are discussed based on the hydrogen passivation model, i.e. the dehydrogenation and hydrogenation occur reversibly and result in activation and passivation of nitrogen accepters, respectively.