THE CHEMICAL ETCHING OF MNXCD1-XTE SINGLE CRYSTALS WITH HNO3 – KI – DIMETHYLFORMAMIDE SOLUTIONS

Abstract

In the conditions of constant development of electronics and semiconductor technology, which has entered every branch of industry, technology and everyday life, there is need to create reliable microcircuits, sensors and working elements. Solid solutions based on cadmium telluride are widely used, which have the ability to conduct electric current under the influence of short waves. To obtain reliable devices, semiconductor single crystals undergo a number of mechanical, chemical-mechanical and chemical treatments in order to form a high-quality polished surface of the future substrate for the deposition of nanostructures on future working elements of devices. Solid solutions MnxCd1-xTe are promising for use as diluted magnetic semiconductors. The chemical dissolution of CdTe single crystals, and MnxCd1-xTe solid solutions (x = 0.3, 0.47, 0.5) in HNO3 – KI – dimethylformamide(DMF) solutions has been investigated under reproducible hydrodynamic conditions for the first time. It is shown that the proposed etching compositions have a number of advantages compared to already developed etching mixtures. The influence of the oxidant concentration on the kinetics of dissolution of solid solutions has been established. The kinetic dependences of chemical-dynamic etching in the developed etching mixtures has been determined to establish the compositions of solutions that have polishing properties. Polishing the surface of CdTe single crystals and solid solutions of MnxCd1-xTe in the proposed etchant can be carried out at a content of 12–15 vol. % HNO3 at a speed of 1.0–2.4 μm/min. Chemical-dynamic polishing with the investigated solutions is the polishing speed. Based on the results of the dependence of the dissolution rate on the disk rotation speed for the solution of the composition (in vol. %): 12 НNO3 + 88 KI (DMF), it has been established that the polishing process occurs by the diffusion mechanism, and for Mn0.5Cd0.5Te by the mixed mechanism. It is shown that with an increase in the manganese content in the composition of MnxCd1-xTe single crystals, the dissolution rate of semiconductors increases. The dependence of the kinetics of chemical-mechanical polishing of the studied single crystals on the dilution of the base solution with an organic solvent was established. When the polishing solution is diluted with lactic acid to a ratio of 3 : 2, the speed of chemical-mechanical polishing decreases from 3.0 to 0.5 μm/min. The values of the electrochemical potentials of the dissolution process MnxCd1-xTe solid solutions were measured and it was established that the corresponding cations pass into the solution during polishing. The technology for chemical-dynamic polishing of MnxCd1-xTe single crystals has been developed, according to which polishing must be carried out in a chemical-dynamic polishing installation at a temperature of 293 K and a disk rotation speed of 82 -1.