Electrical characterization of gallium planar-doped ZnSe grown by molecular-beam epitaxy

We report electrical characterization of a series of ZnSe samples which are planar doped by a new approach to doping involving periodic deposition of sheets of Ga on Zn- or Se-rich surfaces. For samples planar doped on Zn-rich surfaces, the mobility could be described by ionized-impurity scattering and polar optical-phonon scattering mechanisms, while planar-doped samples on Se-rich surfaces and uniformly doped samples require additional scattering mechanisms to describe their mobilities. The latter two cases give higher mobilities than the first, a result which is in conflict with the fact that the latter have higher total ionized-impurity concentrations and compensation. These results of higher mobilities along with higher total ionized-impurity concentrations are interpreted as evidence of donor-acceptor pair formation.