High performance In_0.83Ga_0.17As SWIR photodiode passivated by Al₂O₃/SiN_x stacks with low-stress SiN_x films

To develop extended InGaAs photodiode focal plane arrays with large scale and small pixels, a surface passivation film with low stress is necessary. To study the surface bowing of SiN_x passivation film deposited with different conditions by inductively coupled plasma chemical vapor deposition, 2-in. InP samples were first utilized to obtain statistical results. As can be seen from the result, the bowing introduced by the passivation film is reduced to less than 10 μm when applying optimized film deposition conditions, which is a significant optimization. In the further investigation of the passivation effect on the InGaAs photodiode, Al₂O₃/SiN_x stacks were proposed as the passivation layer, and Al₂O₃ was deposited by atomic layer deposition (ALD). Results demonstrate that the photodiodes passivated by the Al₂O₃/SiN_x stacks have lower dark current density, especially at lower temperatures. At 180 K, the contribution of perimeter dark current is reduced by more than one order of magnitude. Theoretical analysis shows that the composite passivation film effectively suppresses tunneling current at 180 K.