While the original focus of this long-standing series from the Materials Research Society was on hydrogenated amorphous silicon, the symposia have now expanded to incorporate microcrystalline silicon. The two, in fact, are very closely connected since the latter material can be grown by making comparatively small changes to the deposition conditions for amorphous silicon. This book offers an interesting variety of papers on deposition techniques, materials properties, characterization methods and devices - nearly all focused on thin-film forms of hydrogenated silicon. Topics include: Staebler-Wronski and fundamental defect studies in amorphous silicon; the story of hydrogen in amorphous silicon; photoelectric properties of amorphous silicon; deposition and properties of microcrystalline silicon; deposition studies for amorphous silicon and related materials; solar cells; thin-film transistors and sensors and novel device concepts.