GROWTH PRESSURE EFFECTS ON SI SI1-XGEX CHEMICAL-VAPOR-DEPOSITION/

We studied the effects of growth pressure on Si1-xGex/Si heterostructu res grown by rapid thermal chemical vapor deposition in the pressure r ange of 6-220 Torr. The material was characterized by photoluminescenc e (PL), x-ray reflectivity, and electrical measurements on resonant tu nneling diodes (RTDs). High quality material was demonstrated througho ut the pressure range, but a weaker PL intensity at higher pressure (2 20 Torr) indicates lower lifetimes. Interface abruptness was degraded at higher pressures due to gas transients. This was confirmed by x-ray reflectivity measurements and the performance of RTDs. We have establ ished a low pressure limit to interface roughness of 0.2-0.5 nm, deter mined by x-ray reflectivity.