Electron Beam Technique for Measuring Microvolt Changes in Contact Potential

Abstract

A low voltage electron beam technique is reported which when coupled with ac detection is capable of measuring periodic changes in contact potential as small as 1.0μV. This sensitivity, which exceeds by a factor greater than 100 the reported sensitivities obtained by other methods, should enhance the usefulness of the contact potential measurement for detailed surface studies, especially in the case of semiconductors. The potential of the technique is demonstrated in the context of high resolution photovoltage measurements in n‐type CdS which may allow for a sensitive form of surface state or surface barrier spectroscopy.