Damage in a gaas surface caused by rf-sputter deposition of s1o₂

Structural and optical changes in a GaAs surface due to rf sputter deposition of S1O2 were investigated by means of transmission electron microscopy (ТЕМ) and spectroscopic ellipsometry (SE). A blight-field image indicates the occurrence of a surface-modified layer of about 7-9 nm thickness in the GaAs surface after S1O2 deposition, at an rf power density of 1.7 W/cm2. A lattice image shows the increased interfacial roughness betweenGaAs and S1O2 upon the deposition. The thickness of the optically-modified layer in SiCb-deposited GaAs is estimated by SE, using the amorphous semiconductor dispersion model. At the lower rf power deposition, the extentsof damage estimated by ТЕМ and SE were found to be enhanced. Both rf-power and Si02-deposition-rate dependences of damage suggest that impingement by non-depositing particles in the initial stage causes surfacemodification.