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High resistive and photosensitive CdTe doped with In aimed for fabrication of X- and gamma-ray detectors was produced by Vertical Gradient Freeze method. A complex investigation of defects and compensation by a number of optical and photoelectrical mapping methods was performed. A model of energy levels dominating the recombination processes in the material was elaborated, where the role of In, and related complexes as well as native defects (Cd vacancy and its compexes) is discussed. Index Terms--Defect levels, self-compensation, semiinsulating CdTe.

Quasi-chemical formalism is used to evaluate high temperature (600[degrees]C-1000[degrees]C) in situ conductivity and Hall effect measurements and simultaneously tellurium atom fraction in CdTe along the three-phase curve. We show that the electric properties can be described only by two native defects--cadmium interstitial as the divalent donor and cadmium vacancy as the divalent acceptor. Close to Te saturation, another native defect must be involved in the model to allow the deviation from the stoichiometry irrespective of the low density of electrically charged defects. Deep divalent donor [Te.sub.Cd] having both levels near or below the midgap best describes all the high-temperature experimental data. Index Terms--CdTe, high-temperature galvanomagnetic properties, native defects, stoichiometry.

A new study uses micro-Raman spectroscopy to investigate the frequencies and damping of the optical phonons A1(LO) and E2 of GaN and AlN in temperatures ranging from 85-760 K.

The conventional compensation model for the high resistivity characteristics of CdTe is based on the presence of a deep acceptor level of the cadmium vacancy in the center of the band gap. A new compensation model based on a deep intrinsic donor level was developed. The compensation model and an appropriate segregation model were used to compute axial distribution of resistivity which were compared with spatially resolved resistivity measurements.

Photoinduced current transient spectroscopy (PICTS) is used to determine the effects of growth methods on compensation defects in samples of CdTe:Cl. At temperatures between 100 and 140 Kelvin, three distinct traps lead to PICTS signal in every CdTe:Cl sample. A cross section and an activation energy, which is almost similar for the various samples, results from only one trap.

Cadmium zinc telluride (Cd1-xZnxTe) crystals, with zinc values from x=0 to x-1 and grown via the travelling heater method (TVM), were examined via low-temperature photoluminescence (PL). Excitonic line broadening effects were observed in the resulting PL spectra and attributed to alloy fluctuations in the bulk-grown crystals. Theoretical analyses of these effects are presented with corresponding calculations for lattice constants, exciton binding energies, band gap and line widths. A linear relation was observed between the lattice constants and alloy composition.