Amorphous-Silicon-Based Devices

Publisher Summary This chapter reviews recent advances in the amorphous silicon (a-Si) device applications. This chapter begins with enumerating some unique advantages of these tetrahedrally bonded amorphous semiconductors and explains some concrete evidence from current technologies. Remarkable progress has been seen in the field of disordered materials in both theoretical and experimental aspects. One major reason for this progress is the great advances made in material preparation technologies. These advances are supported by ultra-high-vacuum techniques, ultra-purification of inorganic elements and precisely synthesized heat-treatment technologies, including the rapid quenching of thin-film materials. The recent discovery of an existence of valence controllability in hydrogen passivated (a-Si) strongly promotes the evaluation of amorphous semiconductor as a new electronic material. This new amorphous material is able to form both p-n and p-i-n junctions and has excellent photoconductivity with a considerably high absorption coefficient. These characteristics, coupled with mass-production capabilities of large-area non-epitaxial growth on any substrate material, strongly satisfy the current need for the development of a low-cost solar cell as a new energy resource. These integrated ideas have opened some other new application fields such as thin-film transistor (TFT), electrophotography, three-dimensional integrated devices, and quantum-well devices.