Adjustable ultraviolet-sensitive detectors based on amorphous silicon

Abstract

Thin-film detectors made of hydrogenated amorphous silicon (a-Si:H) and amorphous silicon carbide (a-SiC:H) with adjustable sensitivity in the ultraviolet (UV) spectrum were developed. Thin PIN diodes deposited on glass substrates in N–I–P layer sequence with a total thickness of down to 33 nm and a semitransparent Ag front contact were fabricated. The optimized diodes with a 10 nm Ag contact exhibit spectral response values above 80 mA/W in the wavelength range from 295 to 395 nm with a maximum of 91 mA/W at 320 nm. For longer wavelengths, the spectral response drops by 50% at 450 nm. Increasing the thickness of the Ag front contact leads to a narrowing of the spectral response at around 320 nm, which allows the adjustment from a broad UV to a selective UV–B-sensitive detector.