Improved performance of GaSb-based MIR photodetectors through electrochemical passivation in sulphur containing solutions

摘要

Sulfur passivation effects on the performance of LPE-grown GaSb/InGaAsSb/AlGaAsSb mesa-type photodiodes operating in wavelengths range 1.9 ― 2.3 μm have been investigated. (NH_4)_2S, Na_2S, and (NH_2)_2CS have been chosen as sulfur sources in either aqueous or C_3H_7OH solutions. Electrochemical passivation of mesa side walls was proven to reduce photodiodes dark current and increasing their differential resistance by a factor of 4. As a result devices characterized by the detectivity of 1.5-2x 10~(10) cmHz~(1/2)/W and dark current density of 20 mA/cm~2 at -0.5V bias have been fabricated and their long-term stability has been proven.