Plasma enhanced chemical vapor deposited SiO2 layers for passivation of InGaAs:Fe metal-semiconductor-metal photodetectors

Results on the passivation and antireflection coating of InGaAs:Fe metal-semiconductor-metal photodetectors using remote plasma-enhanced chemical vapor deposited SiO2 layers are reported. The deposition of SiO2 on the detector surface leads to a reduction of the dark current by nearly two orders of magnitude at 5 V bias. Temperature-dependent measurements of the leakage current characteristics indicate that the Schottky barrier height is substantially lowered near the metallization edges of the reversed biased contact fingers. The effective barrier height in the edge region, which controls the magnitude of the leakage current is determined by activation energy plots to be 0.14 eV for nonpassivated and 0.20 eV for passivated structures, respectively. Apart from the improvement of the dark current characteristics, the SiO2 coating results in a drastic reduction of the photocurrent gain. The long-term stability of the passivation is proved.