Pb1-xSnxSe-on-Si LWIR sensor arrays and thermal imaging with JFET/CMOS read-out

Long wavelength infrared (LWIR) sensor arrays were fabricated in Pb-1-x SnxSe layers grown epitaxially on Si-substrates by MBE. A CaF2 intermediate buffer layer approximate to 30 Angstrom thick was employed for compatibility reasons. The photovoltaic sensors are based on the blocking Pb-contact technique on p-type material. They were fabricated using simple wet-etching process steps only. Cut-off wavelengths were about 10.5 mu m, quantum efficiencies >60%, and resistance-aera products above 3 Omega 2-cm(2) at 90K. A demonstrational LWIR thermal imaging camera was assembled with a 256 element line array with 50 mu m pitch. Low-noise signal processing was achieved with sensors with differential resistances in the 10 kOhm range by using JFET/CMOS technology. For each channel, an integrator, correlated multiple sampling and sample/hold amplifier was used before multiplexing to a common output.