Cohen-Fritzsche and Ovshinsky

The most comprehensive attack on the theoretical problems posed by the existence of liquid semiconductors has been made by Mott (1966, 1967, 1970, 1971). TTie essential features of his model are shown in Figure 7.53 and have been described in detail by Cohen, Fritzsche and Ovshinsky (1969) and by Davies and Mott (1970). and separate the extended from the localized states (shown shaded) and mark the energy at which a substantial drop in the mobility occurs. An additional hypothesis is that the energy range of localised states is somewhat greater in the conduction band than in the valence band, thereby explaining the tendency for liquid semiconductors to exhibit positive thermoelectric powers. All the liquids... 

Figure 8.05 Models for the density of states of an amorphous semiconductor, (a) A true gap in density of states with some band tailing, (b) The Cohen-Fritzsche-Ovshinsky (1969) model of overlapping valence and conduction band tails (After Mott and Davis 1979)...

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