Comparative study of admittance spectroscopy and DLTS in determining trap levels of CdTe-ZnTe heterojunctions

Abstract

A study of deep levels in the depletion region of an n +-CdTe- p-ZnTe heterojunction has been made using admittance spectroscopy (AS) and deep level transient spectroscopy (DLTS) methods. Four trap level signals were observed by both As and DLTS methods. Activation energies, trap densities and capture cross sections of the shallowest and the deepest trap levels of 0.12 and 1.0 eV, determined from AS data, agree well with DLTS results. These are identified as hole traps by DLTS. A reasonable agreement is also found in case of the electron trap level at 0.24 eV. The trap level with an activation energy of 0.58 eV observed from AS has been shown to be a hole type and exhibits a complex behavior in DLTS. The mechanism of the 0.58 eV trap level is discussed in this paper.