GESI-SI STRAINED LAYER SUPERLATTICES GROWN BY LOW-PRESSURE CVD

SiGe-Si and Si-Ge strained-layer superlattices were grown by a low-pressure CVD system (LP-CVD) using Si2H6 (or Si3H8) and GeH4. Their characteristics were studied using TEM observations, X-ray diffraction, AES, RBS, and Raman scattering measurements. It was found that for producing SiGe-Si SLS's, the superlattice periodicity could be controlled in the range of several to several hundred angstroms. It is concluded that interfaces between the SiGe and Si layers are very sharp. The thickness of the interface region, where the Ge content changes, is less than 10 angstrom. On the other hand, for producing Si-Ge SLS's, intermixing of Si and Ge atoms was an inevitable problem. It was, however, found that decreasing the growth temperature reduces effectively the intermixing.