HYDROGEN MICROSTRUCTURE IN HYDROGENATED AMORPHOUS-SILICON

We present a method to determine the local hydrogen bonding structure in hydrogenated amorphous silicon from infrared spectroscopy measureme nts. This approach is based on a different oscillator strength and ref ractive index for hydrogen atoms located in the isolated and clustered phase. It is demonstrated that the density of distributed hydrogen at oms does not exceed 3-4 at.%, independent of the deposition conditions for several deposition techniques. We suggest that changes in the inf rared-absorption strength upon ion bombardment or light soaking can be attributed to a hydrogen exchange between clustered and isolated phas es.