STRAIN EFFECTS IN CDTE SI HETEROSTRUCTURES

Photoluminescence (PL) and spectroscopic ellipsometry measurements on CdTe/Si strained heterostructures grown by molecular beam epitaxy were carried out to investigate the effect of the strain and the dependenc e of the strain on the Si tilted substrates. The results of the PL spe ctra showed that the relative intensity ratio between the peak at 1.45 2 eV and the bound-exciton peak for the CdTe epilayer grown on the Si (100) 1 degrees tilted substrate had a minimum value and that the stra in for the CdTe epilayer grown on the Si (100) 8 degrees tilted substr ate had a minimum value. When rapid thermal annealing (RTA) was perfor med at 55 degrees C, the PL spectra showed that the relative intensity ratio between the peak at 1.452 eV and that at 1.574 eV for the CdTe epilayer grown on the Si (100) 8 degrees tilted substrate had a minimu m value and that the strain for the CdTe epilayer grown on the Si (100 ) 1 degrees tilted substrate had a minimum value. Spectroscopic ellips ometry measurements showed that the spectrum of the dielectric constan t of the CdTe epilayer grown on the Si (100) 8 degrees tilted substrat e is similar to that of the CdTe bulk. These results indicate that the strains in the CdTe layers grown on Si substrates are strongly depend ent on the Si substrate orientation and that the crystallinity of the CdTe epitaxial layer grown on the Si substrate is remarkably improved by RTA. (C) 1997 American Institute of Physics.