Incorporation of AsSe centers in ZnSe far from equilibrium Original Research Article

An experimental technique employing nuclear transmutation to probe the effects of arsenic doping in ZnSe is presented. ZnSe epitaxial layers are grown from elemental Zn and elemental Se that contains the 75Se isotope. Arsenic dopants are incorporated in ZnSe through the decay of 75Se to 75As which proceeds via electron capture. The 118.5 day half-life of the decay allows ZnSe epitaxial layers to be deposited prior to significant arsenic formation so that AsSe dopants are incorporated after all crystal growth processes are complete. Also, the temperature at the time of dopant incorporation is under investigator control. Because the decay process produces nuclear recoils that are far too small to displace the arsenic dopants from their substitutional selenium sites, no post-growth thermal annealing is required. This experimental technique permits a limiting case of far-from-equilibrium doping, and the long half-life of 75Se results in the gradual incorporation of AsSe so that time-resolved studies can be performed. In the experimental work reported here, AsSe centers are introduced in ZnSe homoepitaxial layers in concentrations greater than 1.5×1018 cm−3. Time-resolved low temperature photoluminescence is employed to observe the effects of AsSe doping of ZnSe.