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Modification of the near surface optical and electrical properties of bulk GaSb (100) resulting from a sulphurbased chemical treatment

An alternative sulphur blended [(NH4)2S/(NH4)2SO4] solution is reported for stabilizing the bulk GaSb (100) surface. Scanning electron microscopy of treated surfaces shows a significant improvement in morphology over untreated surfaces. Dektak step profiling reveals that sulphurization causes a non-linear time dependent etching effect accompanied by smoothening of the surface while the photoluminescence is enhanced three-fold after a 30 minute treatment. The surface state density (Nss) distributions were calculated from forward IV characteristics of Au/n-GaSb Schottky structures. Surface state densities of ?1014cm-2, at midgap, were calculated, with treated surfaces showing about 3 times less than untreated. Treatment apparently unpins the Fermi level in Au/n-GaSb Schottky structures as evidenced by a larger barrier height. Additionally, treatment also reduces the reverse leakage current. The reverse current however does not saturate with applied reverse bias. This may be attributed to either quantum mechanical tunnelling or near surface recombination via surface states not completely passivated (or removed) by the sulphurization.

Auteur(s) : DM Murape, N Eassa, K Talla, JH Neethling, JR Botha and A Venter
Pages : 148-152
Année de publication : 2014
Revue : Proceedings of SAIP2012
Type : Article
Mise en ligne par : TALLA Kharouna