High sensitivity graphene-Al2O3passivated InGaAs near-infrared photodetector.

ABSTRACT

InGaAs/graphene Schottky photodiode has a low Schottky barrier height (SBH) which induces high dark current density. In this paper, an Al2O3thin film is inserted between the layer of InGaAs and graphene to suppress the dark current density for nearly two orders of magnitude. As a result, it is a distinct enhancement on the performance that the graphene/Al2O3/InGaAs near-infrared photodetector (NIR PD) under -0.4 V has a better responsivity of 523.77 mA W-1and a better detectivity of 4.42 × 1010cm Hz1/2/W to 1064 nm incident light than the graphene/InGaAs NIR PD. Moreover, graphene/Al2O3/InGaAs NIR PD also has a great response to 1550 nm incident light and the degradation on the device was observed. With the calculation, an increase of 0.122 eV on the Schottky barrier height (SBH) of graphene/Al2O3/InGaAs was founded. The result is expected to promote the application of the graphene NIR PD to the novel sensors.