Search query: Nb-doped single crystalline MoS2 field effect transistor

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abstract: We report on the demonstration of a p type, single crystalline, few layer MoS2 field effect transistor (FET) using Niobium (Nb) as the dopant. The doping concentration was extracted and determined to be ~3 x 1019/cm3. We also report on bilayer Nb doped MoS2 FETs with ambipolar conduction. We found that the current ON OFF ratio of the Nb doped MoS2 FETs changes significantly as a function of the flake thickness. We attribute this experimental observation to bulk type electrostatic effect in ultra thin MoS2 crystals. We provide detailed analytical modeling in support of our claims. Finally, we show that in the presence of heavy doping, even ultra thin 2D semiconductors cannot be fully depleted and may behave as a 3D material when used in transistor geometry. Our findings provide important insights into the doping constraints of 2D materials, in general.
author_names: Saptarshi Das

Marcel Demarteau

Andreas Karl Gehard Roelofs
title: Nb doped single crystalline MoS2 field effect transistor
year: 2015

abstract: This letter demonstrates unipolar p type MoS<sub>2</sub> field effect transistors (p FETs) The p FETs are fabricated using high work function Pt as the contact electrode and p type MoS <sub>2</sub> film as the active channel. The p FETs, with a channel length of 1 <inline formula> <tex math notation="LaTeX"\mu /tex math>/inline formula> m, show an output current of <inline formula> <tex math notation="LaTeX" 10~\mu /tex math>/inline formula> A/<inline formula> <tex math notation="LaTeX"\mu /tex math>/inline formula> m with a drain voltage of 1 V. The Pt electrode, formed by slow electron beam evaporation, shows a contact barrier height of 0.13 eV. In comparison, a faster deposition rate results in a larger resistance and a higher contact barrier of the Pt electrode. Raman characterization provides certain support for the improved contact interface of the slowly deposited Pt electrode, which may be an essential factor in improving current drive.
author_names: Zichao Ma

Lining Zhang

Changjian Zhou

Mansun Chan
title: High Current Nb Doped P Channel MoS2 Field Effect Transistor Using Pt Contact
venue: IEEE Electron Device Letters
year: 2021

abstract: For the first time, we report the successful fabrication of the well behaved field effect transistors based on the Nb doped b Ga2O3 nanobelt mechanically exfoliated from bulk single crystal. The exfoliated b Ga2O3 nanobelts were transferred onto a purified surface of the 110 nm SiO2/Si substrate. These Nb doped devices showed excellent electrical performance such as ultra small cutoff current of ~10 fA, high current on/off ratio of >108, and a quite steep subthreshold swing (SS, ~120 mV/decade) Furthermore, we investigated the temperature dependence down to 200 K, providing insightful information for its operation in the harsh environment. This work lays a foundation for wider application of Nb doped b Ga2O3 in nano electronics.
author_names: Jinxin Chen

Xiao-Xi Li

Jia-Jia Tao

Huiyuan Cui

Wei Huang

Zhi-Gang Ji

Qinglin Sai

Changtai Xia

Hong-Liang Lu

David-Wei Zhang
title: Fabrication of Nb Doped b Ga2O3 Nanobelt Field Effect Transistor and Its Low Temperature Behavior.
venue: ACS applied materials interfaces
year: 2020

abstract: Growth of highly crystalline MoS<inf>2</inf> single crystals with large edge length of ~260 mm was demonstrated via the sulfurization process. The high quality of the MoS<inf>2</inf> atomic layer, exemplified by its optical property and electrical performance, presents a significant step towards scalable preparation of this material. The back gated FETs based on as grown, single layer MoS<inf>2</inf> exhibited the extraordinary high electron mobility value ~90 cm<sup>2</sup>V<sup> 1</sup>s<sup> 1</sup> which is the largest reported to date for as grown, monolayer MoS<inf>2</inf> in a 2 terminal device configuration.
author_names: Shi Wun Tong

Henry Medina

Wugang Liao

C Zhu

Kedar Hippalgaonkar

Dongzhi Chi
title: High Performance Field Effect Transistor based on Large sized Highly Crystalline MoS2 Single Crystal
venue: 2019 Electron Devices Technology and Manufacturing Conference (EDTM)
year: 2019

abstract: We fabricated ferroelectric non volatile random access memory (FeRAM) based on a field effect transistor (FET) consisting of a monolayer MoS2 channel and a ferroelectric PbTiO3 (PTO) thin film of gate insulator. An epitaxial PTO thin film was deposited on a Nb doped SrTiO3 (Nb:STO) substrate via pulsed laser deposition. A monolayer MoS2 sheet was exfoliated from a bulk crystal and transferred to the surface of the PTO/Nb:STO. Structural and surface properties of the PTO thin film were characterized by X ray diffraction and atomic force microscopy, respectively. Raman spectroscopy analysis was performed to identify the single layer MoS2 sheet on the PTO/Nb:STO. We obtained mobility value (327 cm2/V*s) of the MoS2 channel at room temperature. The MoS2 PTO FeRAM FET showed a wide memory window with 17 kO of resistance variation which was attributed to high remnant polarization of the epitaxially grown PTO thin film. According to the fatigue resistance test for the FeRAM FET, however, the resistance states gradually varied during the switching cycles of 109.
author_names: Hyun Wook Shin

Jong Yeog Son
title: Nonvolatile ferroelectric memory based on PbTiO3 gated single layer MoS2 field effect transistor
venue: Electronic Materials Letters
year: 2017

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.
author_names: Sameer Kumar Mallik

Sandhyarani Sahoo

Mousam Charan Sahu

Sanjeev K Gupta

Saroj Prasad Dash

Rajeev Ahuja

Satyaprakash Sahoo
title: Fast transient charge trapping in salt aided CVD synthesized monolayer MoS2 field effect transistor
year: 2020

abstract: gate dielectric, Nb doped STOOver the past several decades, the aggressive scaling ofSi based metal oxide semiconductor field effect transistor(MOSFET) devices has been successfully achieved. Morerecently, however, as the technology node approaches itsphysical limit down to 10 nm regime, alternative methodo logies have been made for further extension of the Moore'slaw, which has mainly focused on implementation of highcarrier mobility channel materials. Of various path findings,the advent of graphene, a fascinating two dimensional (2D)crystal, has received intensive attention, especially due to itsmassless charge carriers.
author_names: Woo Hee Kim

Jong Yeog Son
title: Single Layer MoS 2 Field Effect Transistor with Epitaxially Grown SrTiO 3 Gate Dielectric on Nb doped SrTiO 3 Substrate
year: 2013

abstract: We report the demonstration of an n channel lateral Si tunnel field effect transistor (TFET) with a single crystalline Ge source fabricated using the gate last process. The p+ Ge source was in situ doped and grown at 320degC. An abrupt interface between Ge source and Si channel with type II band alignment and a steep source doping profile ~1.5 nm/decade) formed the tunneling junction. This allows the realization of a TFET with a steep subthreshold swing of 49 mV/decade at room temperature and an ION/IOFF ratio of 107.
author_names: Yan Liu

Hongjuan Wang

Jielu Yan

Genquan Han
title: A Silicon Tunnel Field Effect Transistor with an In Situ Doped Single Crystalline Ge Source for Achieving Sub 60 mV/decade Subthreshold Swing
year: 2013

abstract: In this report, a screening engineered carbon nanotube (CNT) network/MoS2/metal heterojunction vertical field effect transistor (CNT VFET) is fabricated for an efficient gate modulation independent of the drain voltage. The gate field in the CNT VFET transports through the empty space of the CNT network without any screening layer and directly modulates the MoS2 semiconductor energy band, while the gate field from the Si back gate is mostly screened by the graphene layer. Consequently, the on/off ratio of CNT VFET maintained 103 in overall drain voltages, which is 10 times and 1000 times higher than that of the graphene (Gr) VFET at Vsd 0.1 (ratio 81.9) and 1 V (ratio 3) respectively. An energy band diagram simulation shows that the Schottky barrier modulation of CNT/MoS2 contact along the sweeping gate bias is independent of the drain voltage. On the other hand, the gate modulation of Gr/MoS2 is considerably reduced with increased drain voltage because more electrons are drawn into the graphene electrode and screens the gate field by applying a higher drain voltage to the graphene/MoS2/metal capacitor.
author_names: Thanh Luan Phan

Quoc An Vu

Young Rae Kim

Yong Seon Shin

Ilmin Lee

Minh Dao Tran

Jinbao Jiang

Dinh Hoa Luong

Lei Liao

Young Hee Lee

Woo Jong Yu
title: Efficient Gate Modulation in a Screening Engineered MoS2/Single Walled Carbon Nanotube Network Heterojunction Vertical Field Effect Transistor.
venue: ACS applied materials interfaces
year: 2019

abstract: Abstract Epitaxial SrTiO 3 (STO) thin film as a gate dielectric layer was grown on single crystalline (100) Nb doped SrTiO 3 substrate. On the 100 nm thick STO gate dielectric layer, a 5 nm thick phosphorene sheet channel layer was exfoliated from a bulk crystal. A phosphorene field effect transistor (P STO FET) was prepared by the formation of 90 nm thick Au source/drain (S/D) contacts. The P STO FET exhibited the transport characteristics of a p type transistor with a mobility of approximately 376 cm 2 /Vs and an on/off ratio of approximately 10 3 Furthermore, it was experimentally confirmed that the mobility of the P STO FET was significantly influenced by the flatness of the phosphorene sheet.
author_names: Hyun Wook Shin

Jong Yeog Son
title: Phosphorene field effect transistors using high k gate dielectrics of epitaxial SrTiO3 layers grown on Nb doped SrTiO3 substrates
year: 2017