Improved Automatic Four-Point Resistivity Probe

Abstract

A continuously recording automatic four‐point resistivity probe is described. This instrument is the most rapid and convenient means for determining the resistivity profile, and hence the distribution of net extrinsic conduction centers along the length, of a polycrystalline bar or single crystal of semiconductor material. It is the only method available for determining the quality of such material within a very short time of its preparation, and thus is important as a quality‐control tool in any semiconductor crystal growing operation. It is severely limited by three factors: (1) it is only a surface measurement, (2) it gives no information about the degree of compensation existing in the material, and (3) it cannot detect the presence of electrically inactive impurities. When combined with more complete characterization of samples cut from a few discrete points along the crystal, it is invaluable as a means of interpolation between these discrete points.