We have studied the photoluminescence of ZnSe doped by diffusion of Al at high temperature (1000–1100 °C) or by Ga at low temperature (600 °C). The diffused samples are highly conductive (0.1<ρ<10 Ω cm). According to the doping conditions the luminescence, at 300 °K, is dominated by the well-known self-activated orange emission (6300 Å) or by a yellow-green band that we assign to Na-Al complexes. Annealing in zinc atmosphere was found to have a large influence on the photoluminescence of the Ga-doped samples only. Thus, at 300 °K, the annealed samples exhibit a blue intrinsic emission with a strong reduction of the orange or the yellow-green bands; at 77 and 4.2 °K the photoluminescence spectra are dominated by blue lines corresponding, respectively, to free-electron–acceptor or donor-acceptor recombinations. We show that the shallow acceptor involved is Na.

High-quality homoepitaxial layers of ZnSe have been obtained by the metalorganic method. Optical measurements demonstrate the good purity of these samples. Resonant electronic Raman-scattering experiments have allowed the identification of some residual donors and shown that most of them originate in the substrate. A shallow donor, with an ionization energy of about 30.4 meV, not yet mentioned in the literature, has been observed and is believed to be iodine. Excitation Spectroscopy and Selective Pair Luminescence techniques have shown the existence of a new shallow acceptor associated to a donor-acceptor pair transitions band peaking at 2.75 eV, the ionization energy of which would be about 56 meV. The resonant electronic Raman-scattering technique, used here for the first time to investigate donors, appears much more sensitive than classical luminescence to characterize the semiconductor materials.

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For GaInAs/InP junction field effect transistors as well as heterojunction bipolar transistors, the achievement of very low resistivity P type ohmic contact is a very critical step because the Schottky barrier height on these materials is quite high. The realization of a highly doped P+ layer by Zn diffusion in a semi-closed box and the use of MnAu alloy contact have allowed to solve these difficulties : in fact, a contact resistivity as low as 10-7 Ω cm2 has been obtained