Energy lowering 170 Hall

In comparing the results of the quasi-ballistic model with experiment, generally pq[ = 100 cn v s-1 has been used (Mozumder, 1995a) except in a case such as isooctane (Itoh et al, 1989) where a lower Hall mobility has been determined when that value is used for the quasi-free mobility. There is no obvious reason that the quasi-free mobility should be the same in all liquids, and in fact values in the range 30-400 cmV -1 have been indicated (Berlin et al, 1978). However, in the indicated range, the computed mobility depends sensitively on the trap density and the binding energy, and not so much on the quasi-free mobility if the effective mobility is less than 10 crr v s-1. A partial theoretical justification of 100 cm2 v 1s 1 for the quasi-free mobility has been advanced by Davis and Brown (1975). Experimentally, it is the measured mobility in TMS, which is considered to be trap-free (vide supra). 

Fig. 5. Plot of MO energies (Fenske-Hall) for two 50-electron metal tetracarbonyls related by proton transfer away from the metal nucleus (the 4 lowest lying filled MOs and the 16 highest lying unfilled MOs are not shown). Small blocks correspond to a single MO. The larger blocks contain the number of MOs indicated, and the energies of the upper and lower edges are defined by the highest and lowest MO energies for a particular block. The stippled block corresponds to the Co—H bonding MO.

The Alcoa chlorine process uses about 30% as much electrical energy as the Hall-Heroult process. A1C13 melts at a much lower temperature than the Al203/Na3[AlF6] mixture, so less energy is required to heat the electrolysis container. The product, chlorine gas, is recycled in the Alcoa chlorine process, which keeps the cost down. Also the electrodes do not have to be replaced, as they do in the Hall-Heroult process. However, the main disadvantage is that the Alcoa chlorine process is more dangerous to workers since chlorine is a toxic gas. 

In Ref. 54, XRD showed the deposit to be hexagonal CuSe. Analysis of the absorption spectrum gave a direct bandgap of 2.02 eV. As commonly seen for these compounds, there was still strong absorption at lower energies (e.g., at 1.9 eV, the absorption coefficient was >7 X 10" cm ), possibly due to an indirect transition but likely due, at least in part, to free-carrier absorption. From Hall measurements, the doping (acceptor) density was ca. 10 cm (heavily degenerate) and the mobility ca. 1 cm V sec The dependence of film thickness and deposition rate on the deposition parameters has been studied in a separate paper [62]. 

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