IR-sensor array fabrication in Pb 1− xSn xSe-on-Si heterostructures

Abstract

Large line or area arrays of photovoltaic infrared sensors are desired for thermal imaging and spectroscopic applications. The sensor arrays should be arranged on Si-substrates because of size, costs and the possibility to integrate the read-out electronics of large arrays directly into the Si-substrate. We therefore grow narrow gap Pb 1− x Sn x Se layers by molecular beam epitaxy (MBE) on Si(111)-substrates. A CaF 2 epitaxial buffer layer is used for compatibility reasons. Photovoltaic infrared sensor arrays for the 8–12 μm atmospheric window are fabricated in the 2–4 μm thick layers by photolithographic techniques with 8 mask levels and 6 simple wet etching steps. The operability of the sensor arrays is demonstrated by recording thermal images with a simple camera.