Photovoltage Measurements on an Al-Al2O3-Al Thin-Film Sandwich

The photovoltage of an Al-Al2O3-Al thin-film sandwich with an Al2O3 layer of 60 Å was measured as a function of wavelength and incident light intensity; a potentiometer-type technique was used to eliminate the distortion of the photovoltage by the dark current. Photocurrent measurements were performed using chopped light and synchronous detection. From these measurements barrier height and barrier shape of the Al2O3 insulating film were determined. The measurements indicate that photocurrents flow simultaneously in both directions between the electrodes and, in addition, that the attenuation of the hot electrons in the insulating film used is not less than 60 Å.