A strategy of adopting Ga2O3 alloyed
with
Al element to reduce the oxygen vacancy defect density and enhance
the interface barrier height of Ga2O3 heterojunction
is proposed to fabricate deep-UV photovoltaic detectors with high
thermal stability, high photoresponsivity, and fast response speed.
Here, a graphene/(AlGa)2O3/GaN device with a
photoresponsivity of ∼20 mA/W, a rise time of ∼2 μs,
and a decay time of ∼10 ms is presented at 0 V bias. At the
working temperature of 453 K, the device still exhibits a photo-to-dark
current ratio (PDCR) of ∼1.8 × 103, which is
1–2 orders of magnitude higher than that of the reported high-temperature
deep-UV film detectors. By comparing the formation energy of oxygen
vacancy defects and the interface barrier height of the heterojunction
at different temperatures in graphene/Ga2O3/GaN
and graphene/(AlGa)2O3/GaN systems, the strategy
of synthesizing (AlGa)2O3 ternary composite
alloy is proved to be reliable for fabricating high-performance deep-UV
photovoltaic detectors. The method proposed in this paper can provide
reference for the preparation of deep-UV photovoltaic detectors with
high photoresponsivity and thermal stability in the future.
Lutetium oxide (Lu2O3), an ultrawide semiconductor with an intrinsic bandgap of 5.5–5.9 eV, has been proposed as a potential material for a high- performance deep-ultraviolet (DUV) photodetector. Here, crystal oriented Lu2O3 films with bandgap of 5.6 eV are grown on GaN substrates through sputtering Lu2O3 target, based on which a graphene/Lu2O3/GaN DUV photovoltaic detector is constructed with its photoelectric performance being systematically studied. According to our research, under 0 V bias and 185 nm DUV irradiation, this device shows a high photoresponsivity of ∼13.7 μA/W, a short response time of ∼0.4 s, and a high light to dark current ratio of >600, which is about 1 order of magnitude higher than that of a currently reported DUV photovoltaic detector based on other films grown by magnetron sputtering. This research helps to broaden the range of candidate materials for DUV photodetectors and can work as a significant reference to develop the technology for device fabrication.
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