Hydrogen discharge pressure

In a silane-hydrogen discharge the feedstock gases SiHa and H2 take part in all the processes that occur. A large number of reactions have been proposed (see e.g. Kushner [190]). Nienhuis et al. [191] have performed a sensitivity analysis in their self-consistent fluid model, from which a minimum set of reactions have been extracted for a typical low-pressure RF discharge. Tables II and III list these reactions. They will be used in the plasma models described in subsequent sections. The review articles on silane chemistry by Perrin et al. [192] and on hydrogen by Phelps [193] and Tawara et al. [194] have been used. The electron collision data are compiled in Figure 13 [189]. 

The plasma potential determined from I-V data for argon increases linearly from about 24 to 27 V with increasing power at a pressure of 0.05 mbar. At the highest pressure of 0.35 mbar these values have shifted downwards by about 2 V only. For the hydrogen discharge similar behavior is observed, with an increase... 

FIG. 30. Electron (a) and ion (b) density as a function of power for different pressures in the case of a hydrogen discharge. 

Six hydrogen discharge experiments were cairied out at S, 10, IS, 20, 2S and 40 SLPM hydrogen demand. One of these runs was chosen arbitrarily (the 20 SLPM run) to calibrate the numerical model by varying the h and km until the pressure and temperature histories from the model matched the experimental data. The performances of the other five runs were predicted using these coefficients without further adjustment The heat and mass transfer coefficients obtained from the MV model were h = 13.24 x 10 W/cm /K and km = 0.1, and those from CL model were 7.S7 x 10 W/cm /K and km = 0.1. These values were uniquely defined in each case, with both models resulting in the same km> and nearly the same h. The factor of two difference in h was most likely caused by the difference in the plateau heat of adsorption for the two P-C-T models. The CL model had the lower heat of adsorption (by S kJ/mol) and this was consistent with the CL model also resulting in a smaller value of h. 

Figure 15.1 The usable capacity ratio for hydrogen adsorbed in idealized slit pores and idealized nanotube arrays. The discharge pressure is 0.1013 MPa and the temperature is 298 K. The open circles, open diamonds, and open squares are data for slit pores with widths of 6.15, 9.23, and 20.51 A, respectively. The filled triangles and filled circles are data for arrays of (18, 18) and (9, 9) SWNTs, respectively. (Reprinted with permission firom Ref. [48] Copyright 1999 by the American Institute of Physics.)...

Phosphorus and Phosphines.—Red phosphorus is transported, using a low-pressure hydrogen discharge, to give a product purer than the starting material, in amorphous layers. There is evidence for the suggestion that the transport mechanism involves the formation and subsequent decomposition of unstable volatile hydrides. Applications of a low-pressure silent electric discharge in... 

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