High mobility ReSe2 field effect transistors : Schottky-barrier-height-dependent photoresponsivity and broadband light detection with Co decoration

• 2D transition metal dichalcogenides are promising in various electronics and optoelectronics applications and have gained popularity owing to their carrier transport and strong light-matter interactions. To fully realize their potential in field-effect transistors (FETs) and photodetectors, high mobility and high responsivity are imperative. Here, we demonstrate the highest mobility of ∼166 cm2 V-1 s-1 at 200 K for single-layer rhenium diselenide (ReSe2) FETs encapsulated between h-BN flakes at V g = 47 V. The high mobility is attributed to low-resistance contacts of scandium/gold (Sc/Au), with a low Schottky barrier height and reduced charge scattering platform of h-BN. Further, we elucidated the Schottky-barrier-height dependent high photoresponsivity (∼3.2 × 106 A W-1) of few-layer ReSe2 (FL-ReSe2) at 532 nm-wavelength laser light on an h-BN substrate with Sc/Au contacts. Moreover, broadband light detection of undoped and Co-doped few-layer (FL) ReSe2 was performed under different laser wavelengths (400-1100 nm). After the deposition of Co nanoparticles, the photocurrent of FL-ReSe2 increased due to n-doping, as confirmed by the transfer curves of the FL-ReSe2-based undoped and co-doped FETs. Further, the work function decreased from 4.856 to 4.791 eV in FL-ReSe2, as measured by Kelvin probe force microscopy. No light signal was observed at 1100 nm for the undoped ReSe2 (1050 nm < λ cut-off < 1100 nm); however, after doping with Co nanoparticles, the cut-off wavelength exceeded to (λ cut-off > 1100 nm), due to the additional trap states generated in the energy band gap of ReSe2 after Co doping. Further, the transient response of ReSe2 and Co + ReSe2 FETs was estimated so that the rise and decay times are decreased from 1.9 s & 2.7 s to 1.1 s & 1.8 s, respectively. ReSe2 is therefore a promising semiconducting material for electrical and optoelectrical applications.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Nanoteknik -- Nanoteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Nano-technology -- Nano-technology (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Nyckelord

high responsivity

photodetector

rhenium diselenide

Schottky barrier height

transition metal dichalcogenides

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