Although this is the 16th volume in a long-standing and successful series, the focus is no longer limited to hydrogenated amorphous silicon (a-Si:H). The distinction between short- and medium-range order, and between homogeneous and heterogeneous semiconductor materials, is indeed too difficult to maintain. Instead, the volume covers amorphous and microcrystalline silicon from materials physics to new applications. Papers from a joint session with a symposium on Flat-Panel Display Materials and Large-Area Processes are included. The volume also features special focused sessions on heterogeneous materials, color sensors and radiation imaging, and parameter extraction and device modelling. Topics include: amorphous and polycrystalline thin-film transistors; solar cells; color and X-ray sensors, novel devices, luminescence and sensitization; device modelling and parameter extraction; growth, alloys and clathrates; metastability, hydrogen, atomic and electronic structure; defects and charge transport; and heterogeneous silicon - formation, properties and devices.