Abstract
2D Transition Metal Dichalcogenides hold a promising potential in future optoelectronic applications due to their high photoresponsivity and tunable band structure for broadband photodetection. In imaging applications, the detection of weak light signals is crucial for creating a better contrast between bright and dark pixels in order to achieve high resolution images. The photogating effect has been previously shown to offer high light sensitivities; however, the key features required to create this as a dominating photoresponse has yet to be discussed. Here, we report high responsivity and high photogain MoS2 phototransistors based on the dual function of HfO2 as a dielectric and charge trapping layer to enhance the photogating effect. As a result, these devices offered a very large responsivity of 1.1 × 106 A W−1, a photogain >109, and a detectivity of 5.6 × 1013 Jones under low light illumination. This work offers a CMOS compatible process and technique to develop highly photosensitive phototransistors for future low-powered imaging applications.
Highlights
Transition metal dichalcogenides (TMDCs) have been recently studied with great interest due to their unique electronic and optoelectronic properties
TMDCs such as MoS2 hold a promising role in future photodetectors, since they offer attractive features such as high photoresponsivities, low dark currents, and tunable bandgaps via layer thickness for wider optical absorption[11,12]
Doped n++ silicon was used as a back-gate where 10 nm of atomic layer deposition (ALD) HfO2 was deposited as the dielectric layer
Summary
Transition metal dichalcogenides (TMDCs) have been recently studied with great interest due to their unique electronic and optoelectronic properties Unlike graphene, these materials have an intrinsic bandgap that makes them a promising candidate for developing future electronic devices, including transistors[1], integrated circuits[2], and non-volatile memory devices[3]. TMDCs such as MoS2 hold a promising role in future photodetectors, since they offer attractive features such as high photoresponsivities, low dark currents, and tunable bandgaps via layer thickness for wider optical absorption[11,12]. There has been an exploration of different kinds of applications of photogating such as the use of environmental gases to provide molecular gating[18] and dual photogating with optical absorbing insulators[19], there is still a lack of understanding how to control this effect with
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