Low Temperature Growth of Group II–A Fluoride Layers on Silicon as Buffer for Heteroepitaxial IV–VI and II–VI Compound Semiconductors

Abstract

ABSTRACTWe present our new development of low temperature (<450°C) MBE growth of group II-a fluorides on Si (111) and infrared sensor fabrication in Pb1−xSnxSe grown on such fluoride layers. The stacked CaF2-BaF2 buffer helps to overcome the large lattice and thermal mismatch between the Si-substrate and the narrow gap chalcogenide. Despite a rather nominal quality of the low temperature grown CaF2 layer, the 200nm thick epitaxial BaF2 top layer is of good structural perfection as judged from RBS channelling yield, RHEED-patterns and microscopy. The fluoride buffers were successfully overgrown with Pb1−xSnxSe and small IR-sensor arrays with up to 10.5μm cut-off wavelength were fabricated in the layers. The performance of these sensors is as good as for sensors fabricated with the high temperature buffer layer growth process.