The relationship between deep-level defects and high resistivity characteristic in CdZnTe crystals

Abstract

The internal defects of CdZnTe crystals grown by the modified vertical Bridgman (MVB) method act as trapping centers or recombination centers in the band gap, which have effects on its resistivity. The relationship between deep-level defects and high resistivity characteristic in Cd0.9Zn0.1Te:In single crystal was studied. The deep-level defects were identified by thermally stimulated current (TSC) spectroscopy and thermoelectric effect spectroscopy (TEES) in the temperature range of 18–315 K. The trap-related parameters, e.g., activation energy, capture cross section, trap density were characterized by the simultaneous multiple peak analysis (SIMPA) method and Arrhenius fitting. The deep donor level (\({{E}_{\text{DD}}}\)) dominating dark current was about 0.664 eV near the middle gap by fitting the plots of the natural logarithm of dark current intensity ln(IDC) versus 1/(kT). The doubly ionized Te antisite (\(\text{Te}_{\text{Cd}}^{\text{2+}}\)) below the conduction band acting as a deep donor level was mainly the origin of \({{E}_{\text{DD}}}\) level. The energy value of Fermi-level was about 0.671 eV characterized by current–voltage (I–V) measurements of temperature dependence in the temperature range from 275 K to 315 K. The resistivity was about 8.17 × 109 Ω·cm measured by I–V measurement at room temperature. The high resistivity performance of Cd0.9Zn0.1Te:In crystal is mainly due to the Fermi-level pinned near the middle gap by the \({{E}_{\text{DD}}}\) level.