Very high resolution detection of gamma radiation at room-temperature using p-i-n detectors of CdZnTe and HgCdTe

High-energy photon detectors have been constructed by engineering and fabricating p-i-n diode structures consisting of bulk CdZnTe and epitaxial HgCdTe. The p-i-n structure was obtained by liquid-phase epitaxial growth of p and n doped HgCdTe layers on “intrinsic” CdZnTe material about 1 mm thick and approximately 25 mm square. Curve tracing shows I-V curves with diode characteristics having resistivity above 10¹¹Ω-cm and leakage current of <400 pA to about -60 V reverse bias on a typical rest piece approximately 5×8×1 mm. Spectra of similar test pieces have been obtained at room temperature with various nuclear isotopic sources over the range of 22 keV to 662 keV which show exceptionally high energy resolution. Resolution as good as 1.82% FWHM was obtained for the 356 keV line of ¹³³Ba with a P/V=3.4. The performance of these detectors combined with contemporary infrared technology capable of fabricating 2D arrays of these II-VI materials opens up manifold exciting applications in astrophysics, medical, industrial, environmental, and defense spectroscopy and imaging