An amorphous-to-crystalline phase transition within thin silicon films grown through ultra-high-vacuum evaporation on fu
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An amorphous-to-crystalline phase transition within thin silicon films grown through ultra-high-vacuum evaporation on fused quartz substrates Farida Orapunt1, Li-Lin Tay2, David J. Lockwood2, Jean-Marc Baribeau3, Joanne C. Zwinkels2, Mario Noël2, and Stephen K. O’Leary4 1 Faculty of Engineering and Applied Science, University of Regina, Regina, Saskatchewan, Canada S4S 0A2 2 Measurement Science and Standards, National Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6 3 Information and Communication Technologies, National Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6 4 School of Engineering, The University of British Columbia, Kelowna, British Columbia, Canada V1V 1V7 ABSTRACT A number of thin silicon films are prepared through ultra-high-vacuum evaporation on optical quality fused quartz substrates with different growth temperatures. Through an analysis of grazing incidence X-ray diffraction results, a phase transition, from amorphous-to-crystalline, is found corresponding to increases in the growth temperature. The corresponding Raman spectra are also observed to change their form as the films go through this phase transition. Using a Raman peak decomposition process, this phase transition is then quantitatively characterized through the determination of the amount of intermediate-range order and the crystalline volume fraction for the various growth temperatures considered in this analysis. The possible device consequences of these results are then commented upon. 1. INTRODUCTION Thin-film silicon remains a current focus of research interest. Today’s device quality thinfilm silicon is typically prepared through the decomposition of silane gas within a plasma [1]. The material that arises, which is commonly referred to as hydrogenated amorphous silicon (aSi:H), has traditionally been viewed of as a disordered network, comprised mostly of silicon and hydrogen atoms [2], although recent analyzes have added further nuance to this perspective [3,4,5]. The hydrogen atoms found within this material passivate the silicon dangling bonds that are present and are thus responsible for the favorable electronic properties of a-Si:H [6,7]. Unfortunately, hydrogen atoms, being light and mobile, are also held responsible for an instability that leads to a deterioration in the electronic characteristics of a-Si:H upon exposure to light [8,9,10]. This has encouraged researchers to seek alternate forms of thin-film silicon that still retain the favorable properties of conventionally prepared a-Si:H but without this instability. In order to address this matter, a number of alternate deposition approaches for the preparation of thin-film silicon have been devised in more recent years. Hot-wire deposition was introduced as a means of preparing thin-film silicon in the late 1990s, the resultant material being found to be more stable than conventional forms of a-Si:H [11]. Through the hydrogen dilution of the silane flow within a plasma deposition chamber, a form of thin-film silicon, comprised of silicon nano-crys
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