Surface states and passivation of p-Cd0.9Zn0.1Te crystal

Angle-resolved photoemission spectroscopy is used to characterize the surface states of the clean p-CdZnTe surface. A 0.8 eV surface band with the peak at 0.9 eV below the Fermi level is identified. The surface electron density is about 6.9×1014 electrons/cm2. By comparing the X-ray photoelectron spectroscopy spectrum of etched and passivated surfaces of p-CdZnTe, it is found that passivation with NH4F/H2O2 introduced TeO2 oxide film with the thickness about 3.1 nm on p-CdZnTe surface. Meanwhile, Photoluminescence spectra confirmed that passivation treatment minimized the surface trap states density and decreased the deep level impurity defects related to Cd vacancies.