SULFUR PASSIVATION OF INAS(SB)

The sulphur passivation for the InAs surface was studied by photolumin escence (PL) and spectroscopic ellipsometry (SE). Effects of the treat ment are compared with I-V characteristics and photoresponse (PR) of M ESA structure devices fabricated with LPE multilayer of InAs1-y(Sb-y). It is expected that the dangling bonds at the surface are terminated in the forms of S-In, S-As and S-Sb bonds by the passivation, which re sults in a remarkable decrease of surface recombination center density . This phenomenon was confirmed by observing increases of PL intensity and of the PR of photodiodes. Four order reductions of dark current a nd remarkable increase of PR have been observed on sulphur passivated photodetectors. Stability of the effect of the sulphur passivation was also examined by SE as well as PR measurements. SE measurements showe d that dielectric function of the surface layer for the InAs wafer has no absorption in the measured spectral range between 1.5 and 5.5 eV. After sulphur passivation, optical absorption appeared due to submonol ayer sulphur atoms in good agreement with the results obtained from th e InAs(Sb) photodetectors.