| The electronic, optical, and structural properties of amorphous and nanostructured hydrogenated silicon thin films are examined through a variety of characterization tools, including measurements of the dark conductivity, the photoconductivity, the thermoelectric power, the 1/f noise observed in conductance fluctuations, and the infrared and optical absorption. The characterization of these materials is performed with the aim of addressing several important questions regarding the influence of the long range fluctuations of the conductance band mobility edge. First, the question of whether or not a change in the long range disorder accompanies the light-induced degradation of these materials, termed the Staebler-Wronski effect, is addressed. Second, we discuss the utility of the 1/f noise, observed in amorphous silicon (a-Si:H) to display non-Gaussian characteristics, as a probe of the long range disorder. The noise properties observed in a-Si:H will also be compared to the noise observed in amorphous silicon nano-particles (about 150 nm in size). Lastly, the changes in film properties that result from the introduction of nano-sized crystallites into otherwise amorphous materials (forming nano-structured films) will be examined. Of particular interest to this final question is whether or not nano-structured films may be synthesized in such a way as to reduce or eliminate the light-induced degradation associated with the Staebler-Wronski effect without also reducing the sample quality. |
