Monolithic Pb1-xSnxSe on Si Infrared Sensor Array for the 8-12 μm Range

Linear photovoltaic IR-sensor arrays for the 8-12 ??m wavelength range have been fabricated for the first time in narrow gap Pb1-xSnxSe layers grown heteroepitaxially on Si(111) substrates. Heteroepitaxy was achieved using stacked intermediate CaF2-BaF2 buffer layers. Both, the 2000 ?? thick fluoride buffer layer and the Pb1-xSnxSe were grown by molecular beam epitaxy (MBE). Differential resistance times area products (RoA) are up to 0.3 ??cm² at 77 K. This corresponds to junction noise limited detectivities of 2.4??10¹⁰ cm ??Hz/W which are only 5-10 times lower than those of state of the art Hg1-xCdxTe sensors on non Si substrates with the same cut-off wavelength, but still above the 300 K background noise limit.