Totally relaxed GexSi1−x layers with low threading dislocation densities grown on Si substrates

Abstract

We have grown compositionally graded Ge_xSi_1−x layers on Si at 900 °C with both molecular beam epitaxy and rapid thermal chemical vapor deposition techniques. Triple‐crystal x‐ray diffraction reveals that for 0.10<xxSi_1−x cap layers grown on these graded layers are threading‐dislocation‐free when examined with conventional plan‐view and cross‐sectional transmission electron microscopy. Electron beam induced current images were used to count the low threading dislocation densities, which were 4×10⁵±5×10⁴ cm⁻² and 3×10⁶±2×10⁶ cm⁻² Eq. 2×10⁶ cm⁻² for x=0.23 and x=0.50, respectively. Photoluminescence spectra from the cap layers are identical to photoluminescence from bulk Ge_xSi_1−x.