Spectroscopic Study Of Hydrogen Induced Defect In A-Ge-H

Total yield photoelectron spectroscopy has been used to study the electronic structure change of UHV evaporated a-Ge subjected to posthydrogenation and various annealing cycles. We identify in R.T. hydrogenated a-Ge:H a new hydrogen induced defect at about Eυ + 0.45eV, which can be healed upon 300° C annealing. This new defect accounts for the defect density gradient of hydrogenated amorphous semiconductors, spanning the range from ∼ 1018 cm−3 at the growing surface to 1018–1015 cm−3 in the bulk, depending on growth condition and time. The origin of this new defect is discussed.