Correlation of Space Charge Limited Current and γ-Ray Response of CdxZn1-xTe1-ySey Room-Temperature Radiation Detectors

In this letter we report a direct correlation between the space charge limited current flow and radiation detection properties of Cd
_x
Zn
_1-x
Te
_1-y
Se
_y
(CZTS) detector. CZTS is a recently discovered quaternary wide bandgap semiconductor for room-temperature gamma photon detection. The CZTS single crystals have been grown in-house using a modified Bridgman technique. Planar detectors were fabricated and characterized in terms of charge carrier flow and radiation detection measurements. An anomalous current flow falling outside the Lampert's triangle in logJ - logV plot, has been observed which is not generally seen in semiconductor detectors governed by space-charge limited current flow mechanism. The anomalous behavior has been attributed to the presence of electron traps. The devices were tested for their radiation detection properties by acquiring pulse height spectra using
²⁴¹
Am and a
¹³⁷
Cs isotopes as a source of alpha particles and gamma photons, respectively. It was further noticed that the only detectors which worked satisfactorily as radiation detectors, did not exhibit the anomalous current flow mechanism.