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 epilay ers by using a very thin amorphous Si film as buffer layer. In this pa per, the impurity properties of this kind of GaAs/Si epilayers have be en studied by using PL spectrum, SIMS and Hall measurement. Compared t o 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 en ergy of 1.462 eV, which is assigned to the band-to-silicon acceptor re combination. The SIMS analysis indicates that the silicon concentratio n in this kind of GaAs/Si epilayers is about 10(18) cm(-3). But its ca rrier concentration (about 4 x 10(17) cm(-3)) is lower than the silico n concentration. The lower carrier concentration in this kind of GaAs/ Si epilayer can be interpreted both as the result of higher compensati on and as the result of the formation of the donor-defect complex. We also found that the high-quality and low-Si-concentration GaAs/Si epil ayers can be regrown by using this kind of GaAs/Si epilayer as substra te. 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 (similar to 200 '').