Effect of surface preparation on the properties of Au/p-Cd1−xZnxTe

The effect of bromine methanol (BM) etching and NH4F/H2O2 passivation on the Schottky barrier height between Au contact and semi-insulated (SI) p-Cd1−xZnxTe (x ≈ 0.09-0.18) was studied through current-voltage (I-V) and capacitance-voltage (C-V) measurements. Near-infrared (NIR) spectroscopy technique was utilized to determine the Zn concentration. X-ray photoelectron spectroscopy (XPS) for surface composition analysis showed that BM etched sample surface left a Te0-rich layer, however, which was oxidized to TeO2 and the surface [Te]/([Cd] + [Zn]) ratio restored near-stoichiometry after NH4F/H2O2 passivation. According to I-V measurement, barrier height was 0.80 ± 0.02-0.85 ± 0.02 eV for Au/p-Cd1−xZnxTe with BM etching, however, it increased to 0.89 ± 0.02-0.93 ± 0.02 eV with NH4F/H2O2 passivation. Correspondingly, it was about 1.34 ± 0.02-1.43 ± 0.02 eV and 1.41 ± 0.02-1.51 ± 0.02 eV by C-V method.