Ž
. Ž . Low-temperature epitaxy LTE of crystalline silicon in the plasma-enhanced chemical vapor deposition PECVD was Ž . investigated using in situ observation of reflection high energy electron diffraction RHEED . Source gases of SiH and H 4 2
Ž .
Ž . mixture were decomposed by radio-frequency RF glow discharge, and an epitaxial layer was grown on a p-type Si 001
ÄŽw x w x. w x4 substrate at a variety of hydrogen dilution ratios, R H q SiH r SiH , ranging from 10 to 200, and at substrate 2 4 4 temperatures, T , ranging from 278C to 5608C. Critical thickness of epitaxy above which polycrystalline growth starts to s occur shows two peaks as a function of growth temperature at 1208C and 4308C. The lower temperature peak appeared at 1208C and the surface has a 1 = 1 structure covered by SiH , while at the higher temperature peak of 4308C the surface has 2 Ž . a 2= 1 1= 2 double domain structure along dimmer rows covered by SiH. In addition, at 4308C, RHEED intensity oscillation with an oscillation period of monolayer was observed. This implies a layer-by-layer growth in the PECVD, and suggests a presence of the surface diffusion of film precursors on the hydrogen-terminated surface. These results are explained in terms of the hydrogen-mediated enhancement of crystal growth corresponding to surface hydride mode.