High performance In0.83Ga0.17As SWIR photodiode passivated by Al2O3/SiNx stacks with low-stress SiNx films

Abstract

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 SiNx 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/SiNx 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/SiNx 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.

High-Performance Shortwave Infrared Detector Based on Multilayer Carbon Nanotube Films

“…31 The thermal noise is defined by (2) where the k is Boltzmann constant, T is the temperature, Δf is the frequency bandwidth, and R 0 is the zero-bias differential resistance of diodes, which is defined by (3) Figure 1e shows the I−V characteristics of CNT photodetectors with different thicknesses in the dark, and the calculated current noise of the CNT photodetectors with a thickness of 2.1, 5.1, and 7.2 nm was about 22, 33, and 40 fA/ Hz 1/2 , respectively (shown in Figure 1f). We can calculate the specific detectivity (D*) by the equation (4) where A is the active area of the detectors in cm 2 and Δf is the bandwidth in Hz. D* is a comprehensive performance parameter, showing the weak light detection ability of the photodetector.…”

“…3 However, they have not been widely employed in the market since this type of photodetector is extremely expensive, particularly the extended InGaAs photodetector (cutoff wavelength exceeds 1.7 μm), which has specific applications in military reconnaissance, gas detection, and communication fields. 4 For the extended InGaAs photodetector, the indium concentration of In x Ga 1−x As must be raised to 80%, which results in a significant lattice mismatch (∼1.85%) between the InGaAs layers and the routinely used InP substrates. 5 Therefore, extended InGaAs photodetector exhibits a larger dark current due to the severe lattice mismatch.…”

“…Due to the strong anti-interference ability and all-weather and all-day utilization properties of the shortwave infrared (SWIR) band (1–3 μm), SWIR detectors are widely applied in environmental monitoring, night surveillance, optical communication, remote sensing, and other emerging fields. , Some traditional photodetectors like InGaAs detectors, with high external quantum efficiency (∼70%), extensive linear dynamic range (∼70 dB), and low dark current, have been commercialized . However, they have not been widely employed in the market since this type of photodetector is extremely expensive, particularly the extended InGaAs photodetector (cutoff wavelength exceeds 1.7 μm), which has specific applications in military reconnaissance, gas detection, and communication fields . For the extended InGaAs photodetector, the indium concentration of In x Ga 1– x As must be raised to 80%, which results in a significant lattice mismatch (∼1.85%) between the InGaAs layers and the routinely used InP substrates .…”