The suppression of leakage current via surface passivation plays a critical role for GaSb based optoelectronic devices. In this study, the sulfur passivation parameters are carefully optimized in this study for improving the performance of GaSb p-i-n devices. Two competing processes are evaluated during the sulfur passivation process: the hydrolysis and oxidation of HS�- ions that aide surface passivation and re-oxidation, respectively. Upon the optimization of sulfur passivation parameters and subsequent encapsulation with ALD Al2O3, the surface resistivity significantly increased from 4.3kΩ∙cm to 28.6kΩ∙cm, leading to 19.1 times drop in dark current at room temperature for the GaSb p-i-n structure. This work provides a repeatable and stable passivation approach for improving the optoelectronic performance of GaSb based devices
