Post-Deposition Annealing and Hydrogenation of Hot-Wire Amorphous and Microcrystalline Silicon Films
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ABSTRACT Amorphous and microcrystalline silicon films deposited by hot-wire chemical vapor deposition were submitted to thermal annealing and to RF and electron-cyclotron resonance (ECR) hydrogen plasmas. Although the transport properties of the films did not change after these postdeposition treatments, the power density of a Ar' laser required to crystallize the amorphous silicon films was significantly lowered by the exposure of the films to a hydrogen plasma. This decrease was dependent on the type of hydrogen plasma used, being the strongest for an ECR plasma with the substrate held at a negative bias, followed by an ECR hydrogen plasma with the substrate electrode grounded, and finally by an RF hydrogen plasma.
INTRODUCTION Hot-wire chemical vapor deposition (HW-CVD) has gained recent interest as a technique which can be used to deposit high-quality amorphous silicon (a-Si:H) and microcrystalline silicon (iic-Si:H) at high growth rates. a-Si:H and ýtc-Si:H have been deposited by HW-CVD from hydrogen and silane decomposed on the surface of a heated tungsten wire. 1-4 High deposition rates (rd >10 A/s) have been obtained for both a-Si:H and pc-Si:H. 4 -7 In addition, the use of high substrate temperatures (Tsub-400-500°C) resulted in a-Si:H with improved stability against lightinduced degradation. 8 The use of high substrate temperatures (Tsub>300°C) with high filament temperatures (Tfil-2500°C) in the absence of hydrogen dilution resulted in films with high growth rates (rd>15 A/s), characteristic of a-Si:H deposited by HW, and high conductivities characteristic of gic-Si:H. 9 The objective of this paper is to study the effects of low-temperature thermal annealing (Tann
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