Abstract
Next-generation electronic and optoelectronic devices require a high-quality channel layer. Graphene is a good candidate because of its high carrier mobility and unique ambipolar transport characteristics. However, the on/off ratio and photoresponsivity of graphene are typically low. Transition metal dichalcogenides (e.g., MoSe2) are semiconductors with high photoresponsivity but lower mobility than that of graphene. Here, we propose a graphene/MoSe2 barristor with a high-k ion-gel gate dielectric. It shows a high on/off ratio (3.3 × 104) and ambipolar behavior that is controlled by an external bias. The barristor exhibits very high external quantum efficiency (EQE, 66.3%) and photoresponsivity (285.0 mA/W). We demonstrate that an electric field applied to the gate electrode substantially modulates the photocurrent of the barristor, resulting in a high gate tuning ratio (1.50 μA/V). Therefore, this barristor shows potential for use as an ambipolar transistor with a high on/off ratio and a gate-tunable photodetector with a high EQE and responsivity.
Highlights
Graphene, a two-dimensional (2D) carbon atomic crystal, has attracted substantial interest for electronic applications[1] owing to its high intrinsic carrier mobility[2], excellent mechanical flexibility[3], optical transparency[4], and unique ambipolar transport characteristics[5]
The graphene/MoSe2 barristor device was illuminated by a diffraction-limited laser while the device conductance was recorded as a function of the laser spot position
Because the photocurrent is influenced by the potential profile, an scanning photocurrent microscopy (SPCM) image can provide information on the local potential profile
Summary
A two-dimensional (2D) carbon atomic crystal, has attracted substantial interest for electronic applications[1] owing to its high intrinsic carrier mobility[2], excellent mechanical flexibility[3], optical transparency[4], and unique ambipolar transport characteristics[5]. Graphene photodetectors, which typically use the local potential gradient near the graphene–metal junctions, have shown low external quantum efficiency (EQE) and responsivity owing to poor absorption and low built-in potential[14]. To overcome this problem, graphene photodetectors require extensive junctions rather than local junctions, as well as high mobility and a high built-in potential. Unlike graphene-based lateral photodetectors, which have a rather small photosensing active area near the
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