Magnetoresistance in Amorphous Semiconductors
The first measurement of the magnetoresistance (MR) for amorphous semiconductors was made by Mell and Stuke (1970) and Mell (1974) for amorphous Ge, Si, InSb and GeTe in the variable range hopping (VRH) conduction regime. The typical field dependence of MR for their evaporated a-Si sample is as follows: Below about 1kg the MR increases approximately proportional to the absolute value of the field, then goes through a maximum and finally decreases down to negative values at high fields. The positive contribution to MR increases with decreasing temperature and the absolute value of the negative contribution to MR also increases with decreasing temperature which is clearer in the case of a- Ge. Note that qualitative features of these field- and temperature- dependences are similar to those observed in the Anderson localized regime (Kobayashi and Muto,1979; Onuki et al., 1980).
KeywordsLocalization Length Amorphous Semiconductor Critical Path Method Random Walk Approach Crossover Field
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