The deep levels in GaTe single crystal have been investigated by deep-level transient spectroscopy measurements. The hole-trapping level is detected at 0.8 eV above the valence band. It is found that the deep level is associated with the defect or defect complex and the concentration increases with increasing annealing temperature.

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A polytype of InSe single crystals is determined to be of y-type by means of X-ray Laue and diffractometer measurements. Polarized Raman scattering studies are carried out a t room temperature and the spectra are analysed by using the normal modes of y-InSe. Two Raman lines of the A, mode (118,228 cm-l) and two of the E mode (43, 180 cm-l) are observed. An additional Raman line a t 214 cm-l is attributed to an LO phonon with E symmetry.Ein Polytyp der InSe-Einkristalle wird als y-Typ durch die Rontgenuntersuchung mit der Laue-Kamera und dem Diffraktometer bestimmt. Polarisierte Raman-Messungen werden bei Zimmertemperatur durchgefiihrt und die Raman-Spektren mit dem Schwingungstyp des y-InSe analysiert. Zwei Ramanlinien der A,-Mode (118, 228 cm-1) und zwei der E-Mode (43, 180 cm-l) werden beobachtet. Eine zusltzliche Ramanlinie bei 214 cm-l wird auf ein LO-Phonon mit E-Symmetrie zuriiGgefuhrt.

Zinc (Zn) is doped into GaSe single crystals grown by the Bridgman technique in a wide range from 0.005 to 0.5 at. % to the stoichiometric melt. Radiative recombination mechanisms have been investigated by using photoluminescence (PL) measurements. The PL spectra in Zn-doped samples at 77 K are dominated by three emission bands at 1.75, 1.63, and 1.27 eV. The 1.63 and 1.27 eV emission bands are enhanced with the increase in the amount of Zn. In addition to the results of Hall effect measurements, it is found that the 1.63 and 1.27 eV emission bands are associated with the acceptor levels at 0.12 and 0.3 eV above the valence band, respectively. For the 1.27 eV emission band, the temperature dependences of the PL intensity, peak energy, and half-width are characterized by the configurational coordinate model. 4125