Improvement of CdTe substrate quality by acoustic treatment

Abstract We have developed a method for removal of intrinsic defects and copper from p-CdTe single crystals grown by the Bridgman method. Based on the results of Auger Electron Spectroscopy, Energy Dispersive Spectroscopy and Scanning Electron Microscopy, it has been established that acoustic vibrations of modest power level result in an appreciable enrichment of the crystal surface by Te and the development of a surface relief. In particular, the appearance of a system of parallel lines coinciding with the 〈1 1 0〉 direction and the emergence of numerous small craters and fairly extended Te precipitates have been observed. Complex kinetics of the sample conductivity has been revealed. Finally, two month after acoustic treatment, the sample conductivity decreases at least by a factor of 3–4. Once the defects are accumulated in the surface layer, they can be removed by polishing followed by etching in bromine–methanol.