PROPERTIES OF EPITAXIAL PB1-XSNXSE ON CAF2 COVERED SI(111) SUBSTRATES

Epitaxial narrow gap Pb1-xSnxSe layers on Si-substrates are used for i nfrared focal plane arrays for thermal imaging in the 8-12 mu m wavele ngth range, The density of threading dislocations in the 3-4 mu m thic k layers due to the lattice mismatch is about 3 X 10(7) cm(-2), in acc ordance with the width of X-ray rocking curves (100 arcs range). These narrowest widths are obtained only in layers which exhibit high carri er mobilities. Due to the thermal expansion mismatch, misfit dislocati ons formed during growth glide on each temperature change along the {1 00} main glide planes. The interaction probabilities of such crossing dislocations leading to strain hardening is extremely low, a rough est imate leads to a value of 10(-5), This is because the cumulative plast ic deformation (applied by repeated temperature cycling) is as high as 500%.