Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userFast transient charge trapping in salt-aided CVD synthesized monolayer MoS2 field-effect transistor
334
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Atomically thin semiconductors have versatile future applications in the information and communication technologies for the ultimate miniaturization of electronic components. In particular, the ongoing research demands not only a large-scale synthesis of pristine quality monolayer MoS2 but also advanced nanofabrication and characterization methods for investigation of intrinsic device performances. Here, we conduct a meticulous investigation of the fast transient charge trapping mechanisms in field-effect transistors (FETs) of high-quality CVD MoS2 monolayers grown by a salt-driven method. To unfold the intrinsic transistor behavior, an amplitude sweep pulse I~V methodology is adapted with varying pulse widths. A significant increase in the field-effect mobility up to ~100% is achieved along with a hysteresis-free transfer characteristic by applying the shortest pulse. Moreover, to correlate these results, a single pulse time-domain drain current analysis is carried out to unleash the fast and slow transient charge trapping phenomena. Furthermore, rigorous density functional theory (DFT) calculations are implemented to inspect the effects of the Schottky barrier and metal-induced gap states between drain/source electrode and MoS2 for the superior carrier transport. Our findings on the controllable transient charge trapping mechanisms for estimation of intrinsic field-effect mobility and hysteresis-free transfer characteristic in salt-assisted CVD-grown MoS2 FETs will be beneficial for future device applications in complex memory, logic, and sensor systems.
rate research
Read More
We study field effect transistor characteristics in etched single layer MoS2 nanoribbon devices of width 50nm with ohmic contacts. We employ a SF6 dry plasma process to etch MoS2 nanoribbons using low etching (RF) power allowing very good control over etching rate. Transconductance measurements reveal a steep sub-threshold slope of 3.5V/dec using a global backgate. Moreover, we measure a high current density of 38 uA/um resulting in high on/off ratio of the order of 10^5. We observe mobility reaching as high as 50 cm^2/V.s with increasing source-drain bias.
We report on the fabrication and characterization of synthesized multiwall MoS2 nanotube (NT) and nanoribbon (NR) field-effect transistors (FETs). The MoS2 NTs and NRs were grown by chemical transport, using iodine as a transport agent. Raman spectroscopy confirms the material as unambiguously MoS2 in NT, NR, and flake forms. Transmission electron microscopy was used to observe cross sections of the devices after electrical measurements and these were used in the interpretation of the electrical measurements allowing estimation of the current density. The NT and NR FETs demonstrate n-type behavior, with ON/OFF current ratios exceeding 10^3, and with current densities of 1.02 {mu}A/{mu}m, and 0.79 {mu}A/{mu}m at VDS = 0.3 V and VBG = 1 V, respectively. Photocurrent measurements conducted on a MoS2 NT FET, revealed short-circuit photocurrent of tens of nanoamps under an excitation optical power of 78 {mu}W and 488 nm wavelength, which corresponds to a responsivity of 460 {mu}A/W. A long channel transistor model was used to model the common-source characteristics of MoS2 NT and NR FETs and was shown to be consistent with the measured data.
Monolayer transition metal dichalcogenides (TMD) have numerous potential applications in ultrathin electronics and photonics. The exposure of TMD based devices to light generates photo-carriers resulting in an enhanced conductivity, which can be effectively used, e.g., in photodetectors. If the photo-enhanced conductivity persists after removal of the irradiation, the effect is known as persistent photoconductivity (PPC). Here we show that ultraviolet light (wavelength = 365 nm) exposure induces an extremely long-living giant PPC (GPPC) in monolayer MoS2 (ML-MoS2) field-effect transistors (FET) with a time constant of ~30 days. Furthermore, this effect leads to a large enhancement of the conductivity up to a factor of 107. In contrast to previous studies in which the origin of the PPC was attributed to extrinsic reasons such as trapped charges in the substrate or adsorbates, we unambiguously show that the GPPC arises mainly from the intrinsic properties of ML-MoS2 such as lattice defects that induce a large amount of localized states in the forbidden gap. This finding is supported by a detailed experimental and theoretical study of the electric transport in TMD based FETs as well as by characterization of ML-MoS2 with scanning tunneling spectroscopy, high-resolution transmission electron microscopy, and photoluminescence measurements. The obtained results provide a basis towards the defect-based engineering of the electronic and optical properties of TMDs for device applications.
We report the realization of field-effect transistors (FETs) made with chemically synthesized multilayer 2D crystal semiconductor MoS2. Electrical properties such as the FET mobility, subthreshold swing, on/off ratio, and contact resistance of chemically synthesized (s-) MoS2 are indistinguishable from that of mechanically exfoliated (x-) MoS2, however flat-band voltages are different, possibly due to polar chemical residues originating in the transfer process. Electron diffraction studies and Raman spectroscopy show the structural similarity of s-MoS2 to x-MoS2. This initial report on the behavior and properties of s-MoS2 illustrates the feasibility of electronic devices using synthetic layered 2D crystal semiconductors.
Recent discoveries of the photoresponse of molybdenum disulfide (MoS2) have shown the considerable potential of these two-dimensional transition metal dichalcogenides for optoelectronic applications. Among the various types of photoresponses of MoS2, persistent photoconductivity (PPC) at different levels has been reported. However, a detailed study of the PPC effect and its mechanism in MoS2 is still not available, despite the importance of this effect on the photoresponse of the material. Here, we present a systematic study of the PPC effect in monolayer MoS2 and conclude that the effect can be attributed to random localized potential fluctuations in the devices. Notably, the potential fluctuations originate from extrinsic sources based on the substrate effect of the PPC. Moreover, we point out a correlation between the PPC effect in MoS2 and the percolation transport behavior of MoS2. We demonstrate a unique and efficient means of controlling the PPC effect in monolayer MoS2, which may offer novel functionalities for MoS2-based optoelectronic applications in the future.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
