LPE growth of crack-free PbSe layers on Si(100) using MBE-grown PbSe/BaF2/CaF2 buffer layers

Crack-free PbSe on (100)-oriented Si has been obtained by a combination of liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE) techniques. MBE is employed first to grow a PbSe/BaF2/CaF2 buffer structure on the (100)-oriented Si. A 2.5 mu m thick PbSe layer is then grown by LPE. The LPE-grown PbSe displays excellent surface morphology and is continuous over the entire 8 x 8 mm(2) area of growth. This result is surprising because of the large mismatch in thermal expansion coefficients between PbSe and Si. Previous attempts to grow crack-free PbSe by MBE alone using similar buffer structures on (100)-oriented Si have been unsuccessful. It is speculated that the large concentration of Se vacancies in the LPE-grown PbSe layer may allow dislocation climb along higher order slip planes, providing strain relaxation.