Development of X-ray, Gamma Ray Spectroscopic Detector Using Epitaxially Grown Single Crystal Thick CdTe Films

Abstract

AbstractIn this paper, we review our efforts in the spectroscopic detector development using epitaxially grown thick single crystal films of CdTe. The films were grown on GaAs and Si substrates using metalorganic vapor phase epitaxy growth technique. High crystalline quality thick single crystal CdTe films (>260 μm) were obtained where the growth rates could be varied from 10 to 70 μm/h by adjusting the precursor's flow rates, ratios and the substrate temperatures. Spectroscopic detectors were fabricated in a p-CdTe/n-CdTe/n+-GaAs or p-CdTe/n-CdTe/n+-Si heterojunction diode structure. Both types of detector were capable of detecting and resolving energy peaks from a gamma ray source. However, the spectroscopic performance of p-CdTe/n-CdTe/n+-Si detectors was better than that of the p-CdTe/n-CdTe/n+-GaAs detectors. Details on the growth characteristics, detector fabrication and the detector performance are reported. Furthermore, current challenges in this detector fabrication technique are discussed.