Cadmium zinc telluride has been developed as a room temperature radiation detector in recent years. The issue of decreasing surface leakage current, which affects the energy resolution of radiation response, was investigated extensively by various surface oxidation treatments. In this study, an aqueous solution of hydrogen peroxide (H2O2) was used in the oxidation of CdZnTe wafers in order to decrease surface leakage current. The surface chemical composition and its morphology modification due to this oxidation process were investigated. X-ray photoelectron spectroscopy analysis revealed that the main chemical species left after H2O2 oxidation are TeO2 along with a small amount of a Cd-related oxide. We found no obvious evidence of the presence of Zn-related oxides. The oxide thickness reaches a saturation after 5 min of H2O2 oxidation. The atomic force microscopy images revealed that, at this stage of saturation, the surface roughness and the mean diameter of the main features were about 1.3 μm and 97 nm, respectively. The decrease of 37% in the surface leakage current was related to the oxide layers formed by H2O2 oxidation.

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Articles you may be interested inMorphological features related to micropipe closing in 4H-SiC J. Appl. Phys. 98, 034905 (2005); 10.1063/1.1988988 Effect of Ar post-oxidation annealing on oxide-4H-SiC interfaces studied by capacitance to voltage measurements and photoemission spectroscopy J. Vac. Sci. Technol. A 23, 298 (2005); 10.1116/1.1865153 Thermal stability of Pt Schottky contacts to 4H-SiC J. Appl. Phys. 88, 5724 (2000); 10.1063/1.1319165X-ray photoelectron spectroscopy study of the heating effects on Pd/6H-SiC Schottky structure Pd/SiC Schottky diode has been applied as a chemical sensor for hydrogen and hydrocarbon gases at high temperatures. The diffusion and interfacial reactions between the metal thin film and SiC substrate are known to alter the electrical properties of the device. In this work, the morphology and interfacial composition of Pd ultrathin films on 6H-SiC and 4H-SiC are investigated after thermal annealing using atomic force microscopy and x-ray photoelectron spectroscopy. The Pd ultrathin films of about 3 nm thickness are deposited by radio frequency sputtering. The SiC substrates are 3.5°tilted, Si-face, and n-type, 6H-SiC and 4H-SiC, and the Pd thin film deposition and annealing conditions are identical for both samples. The samples are annealed consecutively from 100 to 600°C in air for 30 min. The Pd ultrathin film on 6H-SiC and 4H-SiC has a good uniformity as deposited, and there are no significant morphological changes for either sample at the low annealing temperatures. At 300°C, a nanofeatured layer and Pd 2 Si were formed on both samples. The irregularly shaped cracks on the Pd nanofeatured layer are observed on 4H-SiC substrate, while the Pd on 6H-SiC exhibits a uniform nanofeatured layer. The interaction between Pd and 4H-SiC is more enhanced than between Pd and 6H-SiC. At 500 and 600°C, Pd on both 4H-SiC and 6H-SiC substrates becomes nanosize clusters. Pd 2 Si reacted with SiC to form PdSi at 500°C for Pd/4H-SiC, and at 600°C for Pd/6H-SiC. The surface composition and morphology of Pd/6H-SiC and Pd/ 4H-SiC are almost identical after annealing at 600°C. The Schottky barrier heights are 1.4 and 1.7 eV for Pd as deposited on 6H-SiC and 4H-SiC, respectively. No significant changes in Schottky barrier height are found on either Pd/6H-SiC or Pd/4H-SiC after annealing.