INFLUENCE OF THE DEPOSITION CONDITIONS ON THE OPTOELECTRONIC PROPERTIES OF RF MAGNETRON-SPUTTERED A-SI-H FILMS

We have studied the effect of the deposition conditions on the hydroge n incorporation modes and content and their effects on the optoelectro nic properties of three different series of a-Si:H films prepared by R .F. magnetron sputtering at high substrate temperature (250 degrees C) and high deposition rates (similar to 10 Angstrom/s). We have correla ted infrared absorption measurements with optical transmission and Pho tothermal Deflection Spectroscopy (PDS) experiments. The samples were characterized successively in their as-deposited state and after annea ling at a temperature around 180 degrees C. The results indicate that the modes of H incorporation as well as the hydrogen content in the th ree series are completely different from those observed for the sample s prepared by Plasma Enhanced Chemical Vapour Decomposition of pure si lane (P.E.C.V.D.) at the same substrate temperature. The microstructur e of the films is also different. The density of deep defects measured in the as-deposited is slightly higher in the former case. This densi ty decreases significantly after annealing at 180 degrees C and become s comparable to that obtained for a-Si:H samples prepared by P.E.C.V.D . at 250 degrees C at low deposition rates (similar to 1 Angstrom/s), with however a higher disorder in the R.F. sputtered films.