DEFECT DENSITY OF A-SI-H FILMS GROWN AT HIGH DEPOSITION RATES

The dependence of the Fermi energy, E(F), the defect concentration, N- DB, and the microstructure of a-Si:H films on the deposition rate have been investigated for sets of samples deposited under different condi tions. Film surface topology was studied by atomic force microscopy. W hile E(F) remains unchanged for the samples deposited in the coplanar- type diode system, the films prepared in the coaxial-type diode system show a strong E(F) shift towards the conduction band with increasing deposition rate associated with an increasing N-DB. Based on IR absorp tion and Auger electron spectroscopy data these observations are relat ed to oxygen and nitrogen incorporation. With the supposition that O a cts as a donor and negatively charged dangling bonds are created, the results show a good agreement with the hydrogen-mediated defect creati on model for a-Si:H.