The deep levels present in semiconducting CdTe and semi-insulating CdTe:Cl and Cd0.8Zn0.2Te have been investigated by means of cathodoluminescence, deep level transient spectroscopy (DLTS), photo-induced current transient spectroscopy, and photo-DLTS. The latter two methods, which can be applied to semi-insulating materials, allow to characterize the deep traps located up to midgap and can determine whether they are hole or electron traps. We have identified 12 different traps, some common to all the investigated samples, some peculiar to one of them. A comparison of the results obtained from the various materials is given and the status of defect models is reviewed.

Low temperature annealing of electron irradiation-induced deep levels in 4H-SiC is reported. The major deep level transient spectroscopy peak S2 associated with the energy level at Ec−0.39eV disappears in the temperature range 360–400K, and some rearrangement of the peak S3, associated with the defect Z1∕Z2 with energy level at Ec−0.5∕Ec−0.65eV occurs in the temperature interval 400–470K. A net free charge carrier concentration increase goes along with the disappearance of peak S2 at Ec−0.39eV, whereas the charge collection efficiency of the diode does not experience any significant change. An interpretation of the annealing of peak S2 on a microscopic scale is given.

The effects on 4H-silicon carbide epilayers of irradiation with protons and electrons having particle energies, respectively, of 6.5 and 8.2MeV were carefully studied and critically compared. In detail, the electronic levels associated with the irradiation-induced defects were analyzed by current-voltage characteristics and deep-level transient spectroscopy (DLTS) measurements up to 550K. In the same temperature range the apparent free-carrier concentration was measured by capacitance-voltage characteristics in order to monitor compensation effects due to the deep levels associated with the induced defects. Introduction rate, enthalpy, and capture cross section of such deep levels were compared. We found that a set of deep levels (at ET=0.39eV, ET=0.65eV, and ET=0.75eV) is the same in both cases of proton and electron irradiations, whereas two other pairs of levels (S1, ET=0.20eV and S1*, ET=0.23eV; S5, ET=1.09eV and S5*, ET=0.89eV) appearing in the same temperature range within the DLTS spectra should be associated with different defect complexes according to the irradiation type. Some conclusions regarding the microscopic nature of the defects related to the deep levels have been drawn.

This work describes an experiment on degradation mechanisms of InGaN light-emitting diode LED test structures which do not fulfill the requirements of longlife products. We present a combined capacitance-voltage C-V, deep level transient spectroscopy DLTS, electroluminescence EL, and cathodoluminescence CL study of short-term instabilities of InGaN/GaN LEDs submitted to low current aging tests at room temperature. In the early stages of the aging tests, the EL and CL characterizations showed an optical power decrease, more prominent at low current levels. The C-V profiles indicated that the stress induced an apparent charge increase, well related to the deep level changes detected by DLTS and to the optical power decrease. It is supposed that the main cause of the degradation is the generation of nonradiative paths, due to the generation/ propagation of defects activated by carrier transport

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