Effect of treatment technology for the surface of multicomponent oxide compounds with sillenite structure on the electro

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TERIALS FOR ELECTRONIC ENGINEERING

Effect of Treatment Technology for the Surface of Multicomponent Oxide Compounds with Sillenite Structure on the Electron-Transition Kinetics in Surface Areas A. N. Chaplygin^, E. A. Spirin, and A. S. Sizov Kursk State Technical University, Kursk, Russia ^e-mail: [email protected] Submitted June 6, 2007

Abstract—The regularities in variation of the photocurrent kinetic curve for sillenite crystals are clarified for pulse photoactivation depending on the technological features of formation of their surface areas. A theoretical description of electron transitions corresponding to the experimental data on a sillenite-crystal surface is given. PACS numbers: 81.40.Rs DOI: 10.1134/S1063782608130125

For creation of optically active elements of functional electronics, a promising line of research is the use of multicomponent oxide compounds with sillenite (Bi12RO20, where R represents Si, Ge, or Ti) structure [1, 2]. However, the existing contradictions in the interpretation of electrode phenomena in sillenites, especially under conditions of poor information about the surfaces and interphase reactions on interfaces, restrict the possibilities of practical use of these materials. The purpose of this study is the estimation of the effect of surface-treatment technology on the electrontransition kinetics in surface areas of multicomponent oxide compounds with sillenite structure with the intent of improving the parameters of optoelectronic devices. It is known that a transition layer formed on a solid surface has properties different from those in bulk [3–5]. In this case, the damaged layer (DL) is formed on the sillenite surface as a result of machining, and its thickness depends on the machining modes and attains 30 µm [6, 7]. The investigations were carried out at an experimental installation designed for measuring the photocurrent in a sillenite crystal under photoactivation. Its equivalent measuring electric circuit is shown in Fig. 1. For analysis of photocurrent amplitude–time dependences, the signal from the oscilloscope arrives through the matching module to the computer input (not shown in Fig. 1). In our investigations, we used four groups of samples. The first group is represented by the samples with bilateral multistage chemical–mechanical polishing (CMP); the damaged layer is presented as a weakly deformed sublayer ≈50 nm thick; the clamping electrodes are used. The second group consists of samples

similar to those of the first group, but with the DL thickness as large as 1 µm; the clamping electrodes are used. The third group consists of samples polished with diamond powders by the standard technology, with a DL thickness is as large as 10 µm; the deposited electrodes are used. The fourth group is samples of the third group with a donor impurity (phosphorus) implanted in DL; the clamping electrodes are used. The surface of bismuth silicate crystals was machined by grinding and subsequent polishing with diamond powders. At the stage of finishing treatment, sillenites were exp