Monolithic Pb 1− xSn xSe infrared sensor arrays on Si prepared by low-temperature processes

Abstract

Epitaxial narrow gap lead chalcogenide layers were grown on Si-substrates with the aid of an intermediate epitaxial CaF 2-BaF 2 buffer by molecular beam epitaxy. Maximum growth temperatures were as low as 450°C both for the buffer and lead chalcogenide layer for the first time. Such low temperatures allow fabrication of monolithic IR-sensors on Si-wafers containing already completely processed Si-circuits with a standard Al-metalization. Photovoltaic linear 66 element arrays were fabricated in such Pb 1− x Sn x Se on Si. The high compositional homogeneity achievable in these only 3 μm thick layers is expressed in a spread of the nominally 10.2 μm cut-off wavelength of less than 0.1 μm over the whole array while quantum efficiencies are 0.59 with standard deviation of 0.03, this although the growth and fabrication technique is yet far from being optimized.