Nv. Nguyen et al., SPECTROSCOPIC ELLIPSOMETRY DETERMINATION OF THE PROPERTIES OF THE THIN UNDERLYING STRAINED SI LAYER AND THE ROUGHNESS AT SIO2 SI INTERFACE/, Applied physics letters, 64(20), 1994, pp. 2688-2690
The existence of both the strain and microroughness at the interface o
f thermally grown SiO2 films on Si was ascertained unambiguously for t
he first time by high accuracy spectroscopic ellipsometry. The dielect
ric function of the interface was determined by a comprehensive data a
nalysis procedure. By carefully examining the dielectric function obta
ined by our model, the strain was seen to cause a red shift of 0.042 e
V of the interband critical point E1 compared with the bulk silicon va
lue. The thickness of the interface region was found to be 2.2 nm of w
hich a significant part is due to the strain.