Characteristics and stability of diode type CdTe-based x-ray and gamma-ray detectors

The electrical and spectral properties of the M-p-n structured In/CdTe/Au detectors have been investigated in comparison with the characteristics of In/CdTe/Pt Schottky diode detectors. The high-resistivity (111) oriented Cl-compensated p-like CdTe single crystals were used in both the cases. The CdTe diode structures with a p-n junction were fabricated by the laser-induced doping procedure. The M-p-n and Schottky diodes were examined by measurements of I-V and C-V characteristics and spectra excited by a 57Co radioisotope at room temperature. From the obtained spectrum measurement data, FWHM, shift and peak-to-valley ratios concerning the 122 keV and 14.4 keV peaks were calculated and the time dependences of these parameters were analyzed. Both types of CdTe-based diode detectors showed high rectification properties that allowed to apply higher bias voltage to reach full charge carrier collection thanks to extension of the depleted layer and hence to obtain high energy resolution.