Effects of annealing atmosphere and temperature on acceptor activation in ZnSe:N grown by photoassisted MOVPE

Abstract

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 N2 atmosphere in the temperature range from 500 to 550°C, while they do not if annealed in atmospheres of H2, diethylzinc (DEZn), and dimethylselenide (DMSe) in which hydrogen is contained. The net acceptor concentration NA − ND has reached up to 4 × 1017cm−3 by the thermal annealing at 500°C, but it is lower when annealed at 550°C. By exposing to H2 atmosphere at 350°C, NA − ND decreases with the exposure time. However, it almost recovers to the value obtained by the first annealing in N2, if the layer is annealed again in N2 atmosphere at 500°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 acceptors, respectively.