Development of radiation imaging devices with energy discrimination capability using thick CdTe layers grown on Si substrates by metalorganic vapor phase epitaxy

We present a summary of our work towards developing spectroscopic and nuclear imaging detectors using epitaxially grown thick single crystal CdTe layers on Si substrates. High crystalline quality thick single crystal CdTe layers (>260 μm) were obtained where the growth rates could be varied from 10-70 μm/h by adjusting the precursor's flow rates, ratios and the substrate temperatures. Both high resistivity p-like CdTe layers and highly conductive n+-CdTe layers with controlled electrical properties were obtained using iodine as a dopant, but using different growth conditions. Detectors were fabricated in a p-CdTe/n+-CdTe/n+-Si heterojunction diode structure, which demonstrated their energy discrimination capability by resolving energy peaks from a gamma source. Details on the growth characteristics and the fabrication process for a 2-D imaging array are presented.