Passivation of infrared photodiodes with alcoholic sulfide solution

The effect of passivation with the solution of sodium sulfide (Na$_2$S) in isopropyl alcohol on the room-temperature performance of the GaInAsSb/GaAlAsSb and InAs/InAsSbP photodiodes is investigated. After such a treatment the dark current density of the GaInAsSb/GaAlAsSb photodiodes at a reverse bias of 0.1 V is reduced from 5.5 $\times$ 10$^{-2}$ to 2.1 $\times$ 10$^{-3}$ A/cm$^2$ and a zero-bias resistance-area product $(R_0 A)$ is improved from 1.0 to 25.6 $\Omega$ cm$^2$. For the InAs/InAsSbP photodiodes, the dark current density at $U$ = -0.1 V is decreased from 1.34 to 8.1 $\times$ 10$^{-1}$ A/cm$^2$, while the $R_0 A$ value increases from 4.4 $\times$ 10$^{-2}$ to 7.3 $\times$ 10$^{-2}$ $\Omega$ cm$^2$. The method offers long-term stability of the photodiode performance.