Photovoltaic Action in Graphene–Ga₂O₃ Heterojunction with Deep‐Ultraviolet Irradiation

Abstract

We demonstrate the fabrication of a monolayer graphene/β-Ga 2 O 3 heterostructure and its interesting prospect of producing a suitable Schottky barrier potential for deep-ultraviolet (DUV) responsive photovoltaic device. The transient response behavior shows a faster response time for photovoltaic mode operation of the photodiode. The fast response at a zero bias is due to generation of photocurrent under an internal built-in field in the graphene/Ga 2 O 3 interface without any contribution from the trapped carriers. The fabricated device also shows an excellent photoresponsivity of 6.1 A W À1 with a slower response time at a low reverse bias voltage (À1.5 V). The high photoresponsivity at a bias voltage can be related to carrier multiplication due to carriers trapping/release process. Our findings show that the graphene/β-Ga 2 O 3 heterostructure can be significant for selfpowered/low power consuming DUV detector applications.

A Strategic Review on Gallium Oxide Based Deep‐Ultraviolet Photodetectors: Recent Progress and Future Prospects

“…[ 201 ] have fabricated an all oxide NiO/β‐Ga 2 O 3 (p–n), type II heterojunction with a built‐in voltage of 1.4 V. A developed photovoltaic action leads to a self‐powered behavior in graphene/β‐Ga 2 O 3 heterojunction based PD. [ 63 ] A strain‐free interface between 2H‐MoTe 2 and β‐Ga 2 O 3 leads to a type I band alignment with an abnormal built‐in potential. [ 202 ] This was attributed to the formation of an interfacial layer of MoO x by the authors.…”

“…The data for this figure has been compiled from refs. [16,[41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77].…”

“…Jaiswal et al [200] have deposited Ga 2 O 3 on III-nitrides (GaN/ AlGaN) epilayers on a Silicon substrate and the subsequent detector showed a good spectral response with a low dark current of 12 nA at 20 V. Kokubun et al [201] have fabricated an all oxide NiO/β-Ga 2 O 3 (p-n), type II heterojunction with a built-in voltage of 1.4 V. A developed photovoltaic action leads to a selfpowered behavior in graphene/β-Ga 2 O 3 heterojunction based PD. [63] A strain-free interface between 2H-MoTe 2 and β-Ga 2 O 3 leads to a type I band alignment with an abnormal built-in potential. [202] This was attributed to the formation of an interfacial layer of MoO x by the authors.…”

“…In the case of gallium oxide based SBPDs, both heterojunctions as well as Schottky barriers are employed to realize self-powered devices. Kalita et al [63] have fabricated deep-UV PDs using heterostructures of monolayer graphene/β-Ga 2 O 3 , thereby leading to a photovoltaic action. They have attributed the fast response (rise time ≈0.62 and decay time ≈0.67 s) at zero bias in their device to the generation of photocurrent under an internal built-in field in the graphene/Ga 2 O 3 interface with an open circuit voltage (V OC ) of 0.01 V. A similar photovoltaic action was observed by Chen et al [54] in their Au/β-Ga 2 O 3 nanowires array film based PD.…”

Balancing the Transmittance and Carrier‐Collection Ability of Ag Nanowire Networks for High‐Performance Self‐Powered Ga2O3 Schottky Photodiode

“…[ 37,38 ] 2D materials (e.g., graphene) with high UVC transmittance have been utilized as potential Schottky electrode for excellent solar‐blind photodetection performance, while they are still facing the challenges of mass production. [ 38–40 ] Nanoscale metal thin films, when acting as possible UVC transparent electrode by shrinking the film thickness, exhibit high sheet resistance and high preparation difficulties. [ 38,41 ] Recently, random networks of Ag nanowire (AgNW), with high UVC transmittance, low sheet resistance, excellent mechanical flexibility, and low‐cost preparation, have been considered as ideal electrode material for SBPDs.…”