Silicon from silanes

Viswanathan R, Thompson D L and Raff L M 1984 Theoretical investigations of elementary processes in the chemical vapor deposition of silicon from silane. Unimolecular decomposition of SiH J. Chem. Phys. 80 4230 0... 

The molar ratio of the III compound to the V compound is typically l/lO.t ] To obtain the desired semiconductor properties, dopants are added such as zinc (from diethyl zinc) or magnesium (from bis(cyclopentadienyl) magnesium) for p doping, and silicon (from silane) or selenium (from hydrogen selenide) for n doping. 

To illustrate some typical results, consider the deposition of silicon from silane. The gas-phase reaction mechanism consists of 27 elementary reaction... 

In most cases, CVD reactions are activated thermally, but in some cases, notably in exothermic chemical transport reactions, the substrate temperature is held below that of the feed material to obtain deposition. Other means of activation are available (7), eg, deposition at lower substrate temperatures is obtained by electric-discharge plasma activation. In some cases, unique materials are produced by plasma-assisted CVD (PACVD), such as amorphous silicon from silane where 10—35 mol % hydrogen remains bonded in the solid deposit. Except for the problem of large amounts of energy consumption in its formation, this material is of interest for thin-film solar cells. Passivating films of Si02 or Si02—deposited by PA CVD are of interest in the semiconductor industry (see SEMICONDUCTORS). 

Semiconductors (a) Silicon (from silane) and S10.9H0.1 Photovoltaic solar cells... 

To demonstrate the main features of the flow in horizontal CVD reactors, the deposition of silicon from silane is used as an example (87). The conditions are as follows an 8-cm-wide reactor with either adiabatic side walls or side walls cooled to the top wall temperature of 300 K, a 1323 K hot susceptor (bottom wall), a total pressure of 101 kPa, and an initial partial pressure of silane in H2 of 101 Pa. The growth rate of silicon is strongly influenced by mass transfer under these conditions. Figure 8 shows fluid-particle trajectories and spatially varied growth rates for three characteristic cases. 

C.H.J., The deposition of silicon from silane in a low-pressure hot-wall system../ Crys. Growth 57 259 (1982). 

Comfort JH, Reif R (1989) Chemical vapour deposition of expitaxial silicon from silane at low temperature I very low pressure deposition. J Electrochem Soc 136 2386-2398... 

S. Veprek, M.G.J. Veprek-Heijman, Possible contribution of SiH2 and SiHs in the plasma-induced deposition of amorphous silicon from silane, Appl. Phys. Lett. 56 (18) (1990) 1766. 

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