PHOTOLUMINESCENCE STUDIES ON GAAS/GE/SI AND GAAS/SIGE/GE/SI HETEROSTRUCTURES AFTER ANNEALING AND HYDROGENATION

Photoluminescence (PL) studies are performed on GaAs layers on Si substrates with Ge and SiGe/Ge buffers. The Ge acceptor-related free to bound emission peak at 1.45 eV was caused by Ge which outdiffused from the buffers during the growth. The tensile stress induced in the GaAs epitaxial layer increased after rapid thermal annealing, and returned to its residual value after subsequent atomic hydrogenation. The PL intensities of the neutral carbon acceptor-related emission increased due to the neutralization of carbon ions after hydrogenation. These results indicate that the crystallinity of the GaAs epilayer is improved after annealing and hydrogenation.