Pressure‐Tunable Ambipolar Conduction and Hysteresis in Thin Palladium Diselenide Field Effect Transistors

Abstract

Few-layer palladium diselenide (PdSe 2 ) field effect transistors are studied under external stimuli such as electrical and optical fields, electron irradiation, and gas pressure. The ambipolar conduction and hysteresis are observed in the transfer curves of the as-exfoliated and unprotected PdSe 2 material. The ambipolar conduction and its hysteretic behavior in the air and pure nitrogen environments are tuned. The prevailing p-type transport observed at atmospheric pressure is reversibly turned into a dominant n-type conduction by reducing the pressure, which can simultaneously suppress the hysteresis. The pressure control can be exploited to symmetrize and stabilize the transfer characteristics of the device as required in highperformance logic circuits. The transistors are affected by trap states with characteristic times in the order of minutes. The channel conductance, dramatically reduced by the electron irradiation during scanning electron microscope imaging, is restored after an annealing of several minutes at room temperature. The work paves the way toward the exploitation of PdSe 2 in electronic devices by providing an experiment-based and deep understanding of charge transport in PdSe 2 transistors subjected to electrical stress and other external agents.

Exploring the air stability of PdSe2 via electrical transport measurements and defect calculations

“…Conversely, Bartolomeo et al, report strong pressure-dependent conduction in bulk-like exfoliated crystals where they observed reversible enhanced p-type conduction at atmospheric pressure and enhanced n-type conduction after an extended (10 h) highvacuum exposure. 33 Thus, our study which finds no significant pressure-dependent effects is a bit surprising since, as was recently demonstrated in WSe 2 , 22 thinner flakes are more susceptible to pressure effects than bulk-like flakes.…”

“…Thus this short term effect (<20 min) could be due to trapped charge injection in the underlying SiO 2 layer caused during the repetitive forward sweep measurement from −60V GS to +60V GS . 33 The n-type conduction increases over the first 20 min and remains nearly constant over the next~22 h. Overall, comparing Fig. 1c, d, dramatic degradation from pristine behavior is observed during atmospheric exposure, but arrested if device is held in vacuum indicating atmospheric adsorbents are the cause.…”

“…2c. Recently, Bartolomeo et al 33 studied the hysteresis of multilayer PdSe 2 field effect transistors. They attributed the observed hysteresis to charge trapping at PdSe 2 defects and in the near interfacial SiO 2 gate region.…”

“…14,16,32 Bartolomeo et al, recently explored the effects of external stimuli such as pressure, and optical and electron irradiation on the electrical properties of exfoliated thick (~25 layer) PdSe 2 field effect transistors. 33 Notably they observed a transition from strongly p-type at atmospheric pressure to ambipolar behavior when pumped to~1 × 10 −6 Torr. In this work we explore the effects of short term (90 min) ambient exposures and long term (~1000 h) ambient aging and compare atmospheric ambient pressure versus vacuum (~1 × 10 −5 Torr) environmental effects on the electrical properties of chemical vapor deposition (CVD) grown multilayer PdSe 2 ; furthermore, we investigate the potential to reverse aging effects through annealing in an inert environment.…”

Contact resistance and mobility in back-gate graphene transistors

“…The isolation of graphene [1][2][3] in 2004 and, later on, of h-BN [4], phosphorene [5], S Mo 2 [6][7][8][9][10][11][12][13][14], WSe 2 [15][16][17], e PdS 2 [18,19], PtSe 2 [20,21] etc, has strongly attracted the interest of the material science community to the world of two-dimensional (2D) materials.…”