Effect of Electron Irradiation on the Transport and Field Emission Properties of Few-Layer MoS₂ Field-Effect Transistors

Abstract

Electrical characterization of few-layer MoS2 based field effect transistors with Ti/Au electrodes is performed in the vacuum chamber of a scanning electron microscope in order to study the effects of electron beam irradiation on the transport properties of the device. A negative threshold voltage shift and a carrier mobility enhancement is observed and explained in terms of positive charges trapped in the SiO2 gate oxide, during the irradiation. The transistor channel current is increased up to three order of magnitudes after the exposure to an irradiation dose of 100e -/nm 2 . Finally, a complete field emission characterization of the MoS2 flake, achieving emission stability for several hours and a minimum turn-on field of ≈ 20 V/µm with a field enhancement factor of about 500 at anode-cathode distance of ~1.5 µm, demonstrates the suitability of few-layer MoS2 as two-dimensional emitting surface for cold-cathode applications.

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

“…Differently from similar FETs based on TMDCs like MoS 2 or WSe 2 , the PdSe 2 transistor exhibits a clear ambipolar behavior with a slight electron–hole asymmetry, and prevailing n‐type conduction in high vacuum. The behavior mimics that observed in graphene transistors, with a minimum conduction point (), separating the n‐type conduction (for ) from the p‐type one (for ).…”

“…Figure a also shows that, after irradiation, the transfer characteristic slowly recovers approaching the initial state in a time of the order of hours. The electron beam generates electron–hole pairs in both the channel layer and the underlying dielectric and promotes the formation of defects . This favors charge trapping and degrades the PdSe 2 electrical conductivity.…”

Nanotip Contacts for Electric Transport and Field Emission Characterization of Ultrathin MoS2 Flakes

“…After the irradiation, the curve shows a left shift, which reveals an increased n-type doping of the MoS2. Such doping is due to positive charge accumulation from beam-induced electron-hole pair generation in SiO2 [66,67]. In order to study the properties of the MoS2/W-tip interface and estimate the contact resistance, we varied the distance between the two tips to apply the Transfer Length Method (TLM) [68].…”

Environmental Effects on the Electrical Characteristics of Back-Gated WSe₂ Field Effect Transistors

“…The subthreshold slope = / ( ) is 4 / and 1.5 / , for the p-type and n-type transistor, respectively. The different results from a different trap density at the WSe /dielectric interface, implying a higher trap density when the WSe channel is covered by PMMA, which adds a second interface [43,44]. The trap states manifest also as a hysteresis in the transfer curve, as shown in the inset of Figure 2 (b), due to trapping and detrapping of charge carriers, whose potential adds to that of the back-gate [41,42,45,46].…”