Fabrication and Characterization of Cd_(0.9)Zn_(0.1)Te Schottky Diodes for Nuclear Radiation Detectors

摘要

We have fabricated and characterized cadmium zinc telluride (CZT) Schottky diodes with low reverse leakage current for high resolution radiation detector applications. The diodes were made using Cd_(0.9)Zn(0.1)Te detector grade crystals grown by the low temperature tellurium solvent method. The diodes were characterized using electron beam induced current (EBIC) technique to investigate crystallographic defects. The EBIC images were correlated with transmission infrared (TIR) images of CZT crystals and the EBIC contrast was attributed to the nonuniformities in spatial distribution of Te. Further characterization by the thermally stimulated current (TSC) spectroscopy revealed shallow and deep level centers with activation energies 0.25- 0.4 eV and 0.65 - 0.8 eV respectively, which we attribute to intrinsic defects associated with excess of Te. Pulse height spectra (PHS) measurements were carried out using a ~(241) Am (59.6 keV) radiation source on the Frisch collar radiation detectors made from the suitable portions of the CZT ingot used for Schottky diode fabrication, and an energy resolution of ～4.2% FWHM was obtained.