Photoluminescence spectrum study of the gaas/si epilayer grown by using a thin amorphous si film as buffer layer

Recently, we reported successful growth of high-quality GaAs/Si epilayers by using a very thin amorphous Si film as buffer layer. In this paper, the impurity properties of this kind of GaAs/Si epilayers have been studied by us-ing PL spectrum, SIMS and Hall measurement. Compared to a typical PL spectrum of the GaAs/Si epilayers grown by conventional two-step method, a new peak was observed in our PL spectrum at the energy of 1.462 eV, which is assigned to the band-to-silicon acceptor recombination. The SIMS analysis indicates that the silicon con-centration in this kind of GaAs/Si epilayers is about 10¹⁸ cm^-3. But its carrier concentration (about 4 x 10¹⁷ cm^-3) is lower than the silicon concentration. The lower carrier concentration in this kind of GaAs/Si epilayer can be in-terpreted both as the result of higher compensation and as the result of the formation of the donor-defect com-plex. We also found that the high-quality and low-Si-concentration GaAs/Si epilayers can be regrown by using this kind of GaAs/Si epilayer as substrate. The FWHM of the X-ray (004) rocking curve from this regrowth GaAs epilayer is 118″, it is much less than that of the first growth GaAs epilayer (160″) and other reports for the GaAs/ Si epilayer grown by using conventional two-step method (~200").