Denysyuk R. The interaction of Cd1-xMnxTe solid solutions with iodine-containing (I2 - methanol, I2 - dimethyl formamide) and iodine-evolving (H2O2 - HI - solvent) etching compositions

Thesis is devoted to experimental investigation of chemical interaction of Cd1-xMnxTe solid solutions with iodine-containing (I2 - methanol, I2 - dimethyl formamide) and iodine-evolving (H2O2 - HI - solvent) etching compositions resulting in development of etchants, methods and conditions of these semiconductors surface polishing. Kinetic peculiarities of CdTe and Cd1-xMnxTe dissolution in iodine-containing mixtures: I2-CH3OH, I2-DMFA, I2-HI and iodine-evolving of six ternary systems: 46% H2O2 - HI - oxalic acid, 46% (30%) H2O2 - HI - tartaric acid, 30% H2O2 - HI - lactic acid and 46% (30%) H2O2 - HI - citric acid. Using mathematical planning of experiment 24 surfaces of equal etching rate of CdTe and Cd1-xMnxTe in mentioned above iodine-evolving mixtures were constructed, and polishing, selective and non-polishing solutions in every investigated system were established. The influence of organic acids (oxalic, tartaric, lactic and citric) and H2O2 concentrations on dissolution rate and etching compositions polishing properties is registered. It is established that on increase of Mn content in Cd1-xMnxTe solid solution the rate of crystal dissolution increases as well as concentration areas of polishing solutions. Electrochemical transformations in the process of crystal polishing are established as a result of experimental electrode potentials measurements of the semiconductors self dissolutions processes in polishing etching compositions and their potentials dependence on etching time. The dependence of chemical and mechanical polishing rate on basic polishing H2O2 - HI - organic acid etchants dissolutions with viscous solvents is depicted. The influence of their nature on etching compositions polishing properties and the quality of Cd1-xMnxTe crystal surface is established. Using experimental data, the compositions of etching solutions are optimized, the conditions and Cd1-xMnxTe semiconductor surface processing to form polished surface of high quality with roughness not more then 0.05 microns are worked out. Key words: chemical etching, solid solutions, surface, polishing, etchant compositions, iodine-containing and iodine-evolving etchants.