ANOMALOUSLY HIGH 'MOBILITY' IN SEMICONDUCTORS

In this paper we present a simple model for an inhomogeneous semiconductor which leads to an anomalously high apparent mobility. The model consists of a cylindrically symmetric van der Pauw measurement with a conducting inhomogeneity. This model is analyzed quantitatively and verified experimentally for several measurement configurations. The results cast doubt on the use of a high mobility as an indication of the quality of a semiconductor unless the homogeneity is unambiguously determined or the magnetic field dependence of the Hall constant is carefully examined.