Contact size effects on the van der Pauw method for resistivity and Hall coefficient measurement

Abstract

Effects on van der Pauw's resistivity and Hall coefficient measurement due to finite size contacts with selected shapes on a square sample were investigated. For the sheet resistivity measurement, correction factors for the apparent measured values at zero magnetic field were determined from both electrolytic tank experiments and computerized over-relaxation calculations. For the Hall coefficient, correction factors for the effect of voltage shorting due to current electrodes and for the effect of current shorting due to Hall electrodes were calculated (by use of a fast-convergent over-relaxation technique) through a range of Hall angle from tan θ = 0·1–0·5. The current shorting contribution to the correction factor at zero magnetic field was also closely estimated by use of an electrolytic tank. In the symmetrical structures studied the Hall errors introduced by the voltage and current electrodes were approximately equal. The study shows that contacts of appreciable size relative to that of the sample can be a good approximation to van der Pauw's infinitesimal contact. Thus, one can utilize the simplicity and other advantages of finite size ohmic contacts for these measurements in normal semiconductor materials evaulation and still obtain precise data by using the appropriate correction factors determined in this paper.