The Effect of Thermal Desorption of Water on Surface States on Germanium in Ultrahigh Vacuum

摘要

Large signal alternating current field effect experiments in the dark and under illumination were carried out on 'real' germanium surfaces following a heat treatment in ultrahigh vacuum. After prolonged heating (about 10 hours) at 520 degrees K, the surfaces were slightly p-type, exhibiting 3 to 5 times higher density of traps than prior to heating. Higher temperatures (560 degrees K, 600 degrees K and 640 degrees K) rendered the surfaces more p-type, but caused essentially no change in the density of traps. The observed changes of the electrical properties were correlated to the results of desorption experiments in which a mass spectrograph was employed. The total surface charge was found to increase linearly with the amount of desorbed water (0.00025 negative elementary charges per desorbed water molecule). (Author)