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Fully-encapsulated CZT crystals were grown by vertical Bridgman technique using boron oxide as encapsulant for preventing material decomposition. To detect possible effects of boron on the crystal microstructure, we performed current-voltage measurements and Photo-Induced Current Transient Spectroscopy measurements on samples grown by boron oxide encapsulated vertical Bridgman (set EVB) and standard vertical Bridgman (set VB). In both sets, the well-known A-center and a midgap trap dominate the PICTS spectra. However, significant differences are evident, related to the different defect contents. Our findings indicate that most of the boron atoms are electrically inactive and do not affect the transport properties of the material, confirming that boron oxide vertical Bridgman technique can be adopted for the growth of detector grade CZT crystals. [ABSTRACT FROM PUBLISHER]

We report the results of an experimental study on the radiation hardness of 4H-SiC diodes used as α-particle detectors with 1 MeV neutrons up to a fluence of 8 × 1015 n/cm². As the irradiation level approaches the range 1015 n/cm², the material behaves as intrinsic due to a very high compensation effect and the diodes are still able to detect with a reasonable good Charge Collection Efficiency (CCE = 80%). For fluences > 1015 n/cm² CCE decreases monotonically to ≈ 20 % at the highest fluence. Heavily irradiated SiC diodes have been studied by means of Photo Induced Current Transient Spectroscopy (PICTS) technique in order to characterize the electronic levels associated with the irradiation-induced defects. The dominant features of the PICTS spectra occur between 400–700 K; in this temperature range the deep levels associated with the induced defects play the main role in degradation of the CCE. Enthalpy, capture cross-section and concentration of such deep levels were calculated and we found that two deep levels (Et = 1.18 eV and Et = 1.50 eV) are responsible for the decrease in CCE. They have been associated to an elementary defect involving a carbon vacancy and to a defect complex involving a carbon and a silicon vacancy, respectively. [ABSTRACT FROM AUTHOR]

Although electroless contacts are the most used contacts on II-VI semiconductor materials (CdTe family) to solve many problems, they are difficult to understand and to control. For this paper, we have chosen two II-VI materials, CdTe and ZnTe, and three metals: Au, Pt, and Pd. For the characterization methods, we have chosen Rutherford backscattering (RBS), secondary ions mass spectroscopy (SIMS), and partially Auger for the contacts and interface structures, stoechiometry, and composition profiles. Electrical measurements, PICTS and TEES, are done to find out defect level concentrations and nature, as well as the possible correlation with the composition concentrations. As first parameter change, we have chosen the solution dilution in the electroless deposition process, while the other parameters were frozen. This allows us to drive and to see a drastic variation in the profile of the metal, the two constituent materials and the oxygen in the metal layer. The same has been seen at the interface where the Vc,d concentration profile shows sensible variation too. We have found a clear connection with specific electrical defect concentrations. The validity of these concentration measurements in the bulk are then subject to questions. The comparison with evaporated contacts is done for bulk and surface property separations. Contact induced stress is simulated by static pressure in longitudinal and transversal direction. We have driven out the induced defect natures and concentrations. The limit of operation under stress is also given. [ABSTRACT FROM AUTHOR]

Radiation damage can strongly affect the performance of detectors and we have carried out a systematic study on the effects of different ionizing radiation on CdTe and CdZnTe detectors. In this paper, we present a novel perspective of investigation on the effects of gamma rays, electrons, neutrons, and protons by correlating the "macroscopic" performance of the detectors, characterized by gamma spectroscopy measurements, to the "microscopic" effects of impinging radiation, i.e., to the defective states induced within the crystal lattice, by carrying out photoinduced current transient spectroscopy (PICTS ) analyses. The comparison of the results obtained from CdTe and CdZnTe allows for the identification of the defects that play a major role in degrading the detectors' spectroscopic capabilities. [ABSTRACT FROM AUTHOR]