Two-Stage Mechanism of Nano-Cones Formation by Laser Radiation on a Surface of Elementary Semiconductors and Semiconductor Solid Solutions

Content Provider	Semantic Scholar
Author	Mychko, A.
Copyright Year	1985
Abstract	The basic model used today for description of laser radiation (LR) effects in semiconductors is the thermal model, at least for laser pulse duration till picoseconds [1]. It implies that energy of light is transformed into thermal energy. But it is only the first step in the understanding of this process. So, irradiation of a semiconductor by LR can lead to different results, but sometimes even to opposite results. Experimental results on investigation of the mechanism of nanocones formation on the irradiated surface of Si1-xGex and Cd1-xZnxTe solid solutions have shown that this process is characterized by two stages – Laser Redistribution of Atoms (LRA) and Selective Laser Annealing (SLA). At the first stage of the process, LRA formation of hetero-structures takes place, such as: Ge/Si due to Ge and Si atoms separation in Si1-xGex sample and CdTe/Cd1-x1Znx1Te in Cd1-x0Znx0Te (x1>x0) solid solutions due to separation of Cd and Zn atoms in gradient of temperature takes place. LRA is non linear optical effect: concentration of the redistributed atoms (Ge in the case of GeSi and Cd in the case of CdZnTe) increase with number of laser pulses and in the same timeincrease absorption coefficient of the formed top layer. At the second stage, SLA formation of nanocones on the irradiated surface of a semiconductor takes place by mechanical plastic deformation of the top layer due to relaxation of the mechanical compressive stress arising between these layers due to mismatch of their crystal lattices. SLA occurs due to higher absorption of the laser radiation by the top layer than layer under it. The evidences of these stages will be presented by experimental investigation of Si1-xGex and Cd1-xZnxTe solid solutions irradiated by laser radiation using following methods: microhardness, photoluminescence, Raman back scattering and atomic force microscopy.
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Language	English
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