Low leakage of In0.83Ga0.17As photodiode with Al2O3/SiNx stacks

Al2O3/SiNx stacks were used as the passivation layer to reduce the dark current of extended wavelength In0.83Ga0.17As photodiodes. The Al2O3 and SiNx layers were deposited sequentially by atomic layer deposition (ALD) and the inductively coupled plasma chemical vapor deposition (ICPCVD), respectively. Compared to the single passivation layer of SiNx deposited by ICPCVD, the Al2O3/SiNx stacks result in a more than 20% lower dark current of the In0.83Ga0.17As photodiodes. The substantial dark current reduction can be attributed to lower defect density at the InGaAs/Al2O3 interface and thus lower surface leakage current.