Abstract
Group-10 transition-metal dichalcogenides are puckered van der Waals semiconductors, with a narrow bandgap, envisioned for ultra-broadband infrared (IR) detection. To assess their dynamical transport properties we investigate n-MOSFETs by using microwave admittance spectroscopy. We report on surface channel inversion-depletion-accumulation behaviors with a depletion length of , a mobility of , and a bulk bandgap of . Our 10 µm long devices have an electronic cut-off frequency in the GHz range promising a large gain-bandwidth product, competitive with that of III–V (InAs) and II–VI (HgCdTe) devices. The integration of bulk absorption and surface readout in -MOSFETs is a monolithic geometry suitable for fast IR detection in the application-rich 1– range, which includes molecular spectroscopy, atmospheric communications and thermal sensing.
Highlights
Beyond the mostly investigated group-6 transitionmetal dichalcogenides (TMDs; MoS2, MoSe2, WSe2) [1, 2], noble-metal-based group-10 TMDs (PtSe2, PdSe2, PdTe2) have recently attracted attention due to their high carrier mobility and thicknessdependent bandgap, inherited from their puckered 2D pentagonal structure [3]
In this letter we focus on the low-bias electronic characterization of bulk PdSe2-MOSFETs, equipped with low Schottky-barrier (SB) Pd contacts [19], and compare them with few-layer transistors
PdSe2 transistors are fabricated by exfoliating highquality PdSe2 crystals [4] grown by a self-flux method as described in [4], and transferring them onto large hBN flakes, exfoliated from high-quality hBN crystals grown under high pressure-high temperature as described in [21] acting as bottom-gate dielectric
Summary
Group-10 transition-metal dichalcogenides are puckered van der Waals semiconductors, with a narrow bandgap, envisioned for ultra-broadband infrared (IR) detection. To assess their dynamical transport properties we investigate PdSe2 n-MOSFETs by using microwave admittance spectroscopy. We report on surface channel inversion-depletion-accumulation behaviors with a depletion length of 15 nm, a mobility of 110 cm V−1 s−1, and a bulk bandgap of 0.15 eV. Our. 10 μm long devices have an electronic cut-off frequency in the GHz range promising a large gain-bandwidth product, competitive with that of III–V (InAs) and II–VI (HgCdTe) devices. The integration of bulk absorption and surface readout in PdSe2-MOSFETs is a monolithic geometry suitable for fast IR detection in the application-rich 1–10 μm range, which includes molecular spectroscopy, atmospheric communications and thermal sensing
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