Scanning tunneling microscopy and scanning tunneling spectroscopy were used to study the passivation of atomic-scale defect-induced surface states on cleaved III–V (110) surfaces. This work was based upon the use of thin Si layers which were deposited in situ onto atomically clean surfaces. The simultaneous scanning tunneling microscopic and scanning tunneling spectroscopic measurements permitted the direct correlation of structural and electronic properties at the nanoscopic level. The preferential adsorption of Si clusters onto surface defects was achieved by using high-temperature growth onto GaAs(110) substrates. The scanning tunneling spectroscopic results clearly indicated a local electronic passivation of both step defects and vacancy clusters when the interface was formed at 280C. This was also confirmed at the macroscopic level by using X-ray photo-electron spectroscopy under identical conditions. The results were interpreted in terms of the surface bonding of Si with defect sites. This study was extended to real laser devices, where comparable defect features were observed.

The Passivation of Atomic Scale Defects Present on III–V Semiconductor Laser Facets - an STM/STS Investigation. S.P.Wilks, K.S.Teng, P.R.Dunstan, R.H.Williams: Applied Surface Science, 2002, 190[1-4], 467-74