A STUDY OF LAPPING AND POLISHING DAMAGE IN SINGLE-CRYSTAL CDTE

The surfaces of single-crystal CdTe specimens subjected to lapping and polishing operations were studied. Optical microscopy was used to establish that lapping with an abrasive creates damage principally in the form of microcracks extending below the surface. The depth of damage was similar to that reported for single-crystal Si and was 50 mu m from 240 grit (47 mu m) SiC and 15 mu m from 600 grit (28 mu m) SiC. Polished surfaces were studied using a dislocation revealing etchant. Lapping-induced microcracks could be removed by sufficient polishing with an abrasive, but the specimen always possessed a surface layer of very high dislocation density, with the average depth of the dislocations being a function of abrasive particle size. The maximum dislocation depths were found to be 9 mu m from a 5 mu m Al//2O//3 polishing abrasive and 3 mu m from 0. 3 mu m Al//2O//3.