Stable Field Emission from Layered MoS2 Nanosheets in High Vacuum and Observation of 1/f Noise

Field emission and current noise of hydrothermally synthesized MoS2 nanosheets are investigated in ultra-high-vacuum and industrially suited high-vacuum conditions. The study reveals that the emission turn-on field is pressure dependent. Moreover, the MoS2 nano‐sheets exhibit more stable field-electron emission in high- vacuum than in ultra-high-vacuum conditions. The investigations on field-emission current fluctuations show features of 1/f-type noise in ultra-high-vacuum and high-vacuum conditions, attributed to adsorption and desorption processes. The post-field-emission results indicate the MoS2 nanosheets are a robust field emitter in high-vacuum conditions

Remarkably low turn-on field emission in undoped, nitrogen-doped, and boron-doped graphene

Field emission studies have been carried out on undoped as well as N- and B-doped graphene samples prepared by arc-discharge method in a hydrogen atmosphere. These graphene samples exhibit very low turn-on fields. N-doped graphene shows the lowest turn-on field of 0.6 V/μm, corresponding to emission current density of 10 μA/cm2. These characteristics are superior to the other types of nanomaterials reported in the literature. Furthermore, emission currents are stable over the period of more than 3 h for the graphene samples. The observed emission behavior has been explained on the basis of nanometric features of graphene and resonance tunneling phenomenon

Pulsed Laser-Deposited MoS₂ Thin Films on W and Si: Field Emission and Photoresponse Studies

We report field electron emission investigations on pulsed laser-deposited molybdenum disulfide (MoS₂) thin films on W-tip and Si substrates. In both cases, under the chosen growth conditions, the dry process of pulsed laser deposition (PLD) is seen to render a dense nanostructured morphology of MoS₂, which is important for local electric field enhancement in field emission application. In the case of the MoS₂ film on silicon (Si), the turn-on field required to draw an emission current density of 10 μA/cm² is found to be 2.8 V/μm. Interestingly, the MoS₂ film on a tungsten (W) tip emitter delivers a large emission current density of ∼30 mA/cm² at a relatively lower applied voltage of ∼3.8 kV. Thus, the PLD-MoS₂ can be utilized for various field emission-based applications. We also report our results of photodiode-like behavior in (n- and p- type) Si/PLD-MoS₂ heterostructures. Finally we show that MoS₂ films deposited on flexible kapton substrate show a good photoresponse and recovery. Our investigations thus hold great promise for the development of PLD MoS₂ films in application domains such as field emitters and heterostructures for novel nanoelectronic devices