Determination of pseudogap state density and carrier mobility in rf sputtered amorphous silicon. Quarterly technical progress report, October 1-December 31, 1979

Abstract

Analysis by Secondary Ion Mass spectrometry has shown levels of about 1000 ppM of 0 and other chemical species in our a-Si:H, which is about the same as is found in samples from other laboratories where such measurements have been carried out. There is also an increase in the level of contaminant near the substrate-film interface which is judged to be the likely cause of our hitherto low field effect response. Methods of preparation are being changed in an attempt to eliminate the contaminant. The field effect was also measured near the top surface of the samples, using a teflon insulator. Analysis of these data, following the procedures adopted by others as reported in the literature, indicates densities of states in the pseudogap as low as several times 10/sup 16/ cm/sup -3/. Such densities are comparable with the best that have been published. However, we feel that both the field effect experiment and its analysis (ours and others) are flawed by experimental errors and necessary assumptions. Efforts are being made to reduce these.