The increasing popularity of infrared (IR) detectors in thermal imaging and pollution control is progressively stimulating the industry to enhance the detection efficiency, and ultimately the performance-cost ratio of IR cameras. Developing new IR-sensitive materials, operating at room temperature without cooling, is undoubtedly a winning strategy which this book adopts by investigating the properties of non-crystalline silicon, with emphasis on boron-doped hydrogenated amorphous silicon, used as resistive material for micro-bolometers. The contents are combined in order to drive professionals in IR sensors, as well as material scientists and graduate students in applied physics and engineering, from basic design parameters, such as temperature coefficient of resistivity and noise, down to the specifications for material deposition. Featuring a blend of theory and experiments (Raman spectroscopy, X-ray diffraction, optical absorption and resistivity measurements), the analysis encompasses the effects of BCl3-doping and hydrogenation on the electronic structure, phonon spectra and electrical transport of amorphous and micro-crystalline silicon materials.