Optimization of surface passivation for suppressing leakage current in GaSb PIN devices

Abstract

The suppression of leakage current via surface passivation plays a critical role for GaSb-based optoelectronic devices. In this Letter the authors carefully optimise the sulfur passivation parameters for improving the performance of GaSb p–i–n devices. Two competing processes are evaluated during the sulfur passivation process: the hydrolysis of HS– ions that aide surface passivation and the re-oxidation, respectively. Upon the optimisation of sulfur passivation parameters and subsequent encapsulation with atomic layer deposition Al2 O3, the surface resistivity significantly increased from 4.3 kΩ.cm to 28.6 kΩ.cm, leading to a 19.1 times drop in dark current at room temperature for the GaSb p–i–n structure. This Letter provides a repeatable and stable passivation approach for improving the optoelectronic performance of GaSb-based devices.