Epitaxy of IV-VI materials on Si with fluoride buffers and fabrication of IR-sensor arrays

A review and new results are presented on MBE growth and infrared sensor array fabrication with Pb_1-xSi_xSe layers on Si including a very thin CaF₂ buffer needed for compatibility reasons. Densities of visible defects below 10³ cm^-2 at the surfaces and HRXRD line widths of 105 arc sec (for 3 μm thick layers) indicate a good crystalline quality of the layers which are grown on 3" Si(111)substrates. The induced mechanical strain due to the thermal expansion mismatch relaxes down to cryogenic temperatures even after many temperature cycles. This is due to dislocation glide in the main <110>{100}-glide system even at low temperatures. The layers maintain their quality on temperature cycling, no significant HRXRD line broadening was observed for layers cycled as much as 1400 times between room temperature and 77 K. This despite these layers suffered a cumulative plastic deformation as high as 400%! IR-sensor arrays with up to 256 elements were fabricated using a new delineation technique which is suited for whole wafers and for growth and fabrication on active Si-read-out chips. Preliminary 128x128 pixel LWIR images are presented.