Improved GaSb surfaces using a (NH4)2S/(NH4)2S04 solution

Bulk (100) n-GaSb surfaces have been treated with a sulphur based solution ((NH4)(2)S/(NH4)(2)SO4) to which sulphur has been added, not previously reported for the passivation of GaSb surfaces. Au/n-GaSb Schottky barrier diodes (SBDs) fabricated on the treated material show significant improvement compared to that of the similar SBDs on the as-received material as evidenced by the lower ideality factor (n), higher barrier height (phi(b)) and lower contact resistance obtained. Additionally, the reverse leakage current, although not saturating, has been reduced by almost an order of magnitude at -0.2 V. The sample surfaces were studied by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The native oxide, Sb-O, present on the as-received material is effectively removed on treating with ([(NH4)(2)S/(NH4)(2)SO4]+S) and (NH4)(2)S. Analysis of the as-received surface by XPS, prior to and after argon sputtering, suggests that the native oxide layer is <= 8.5 nm. (C) 2011 Elsevier B.V. All rights reserved.