Graphene/Al2O3/InGaAs-based nanostructures for near-infrared photodetectors passivated by InP layer

In the past decade, graphene-based near infrared photodetectors (NIR PDs) have attracted attention for their high response speed and high responsivity. As a promising graphene-based nanostructure, the InGaAs/Al2O3/graphene device has been proven to have important applications in the detection of the near infrared light. The monolayer graphene and a thin Al2O3 layer could improve the device performance. However, the device degraded the current-voltage (I–V) characteristics. To enhance the resistance of this Schottky nanostructure NIR PD to the irreversible degradation, a layer of p-InP under the SiNx is expected to reduce the defects and enhance the absorption of NIR light. In this work, the Schottky nanostructure NIR PD with the InP layer has a high detectivity of 2.3⨯1013 cm Hz1/2 W−1, a high response speed of 557 ns/3.22 μs, and a high responsivity of 11.23 A/W at −1.5 V and 1.32 A/W at 0 V to 1550 nm infrared light, which is even larger than that of the metal-oxidation-semiconductor (MOS) structure. The wavelength-responsivity (λ-R) characteristics measured by different infrared lasers ranging from 808 nm to 1870 nm indicated a wide response spectrum. Moreover, the phenomenon of the reverse photocurrent was observed and analyzed. •We adopted InP layer to obtain a high-performance graphene/Al2O3/InGaAs near-infrared photodetector.•The responsivity is 11.23 A/W, the response speed is 557 ns/3.22 μs and the detectivity is 2.3⨯1013 cm Hz1/2 W−1 to 1550 nm.•The reverse photocurrent phenomenon of the near-infrared photodetector was found and analyzed.