XPS Analysis and Determination of Surface Damage Layer of CdGeAs2 Single Crystal

An integral CdGeAs2 (CGA) single crystal with the size of Φ15 mm×45 mm was obtained by the modified Bridgman method. For the reasonable application of the CGA crystal, different polishing techniques have been employed in this work. The as-grown ingot was cut and wafers with (101) plane were mechanically polished by means of metallographic abrasive papers. Then the surface element composition and valences of (101) plane on the CGA crystal were analyzed by the X-ray photoelectron spectroscopy (XPS). Finally, the wafers were chemically polished by a bromine-methanol corrosive solution. The samples chemically polished for different time were studied by X-ray diffraction (XRD) and optical microscopy. It is found that after etching by bromine-methanol solution for 50 s at room temperature, the CdGeAs2 wafer has no scratch marks, and possesses a narrow full width at half maximum (FWHM). Meanwhile, the thickness of the surface damage layer of CdGeAs2 wafer was also calculated.