Four-probe measurements of the electrical conductivity of semiconductor layers containing inhomogeneous regions

The possibility of performing four-probe measurements of conductivity of semi-conductor layers containing inhomogeneous regions is evaluated. Exact formulas are obtained for determination of semiconductor conductivity for arbitrary position of the probe near a circular inhomogeneity, and for two probe positions near two circular inhomogeneities. An approximate formula is presented for use with semiconductors containing several inhomogeneous regions. Theory is compared with experimental results.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 30–33, July, 1977.