Iron (III) chloride doping of CVD graphene

Photoinduced Tuning of Schottky Barrier Height in Graphene/MoS2 Heterojunction for Ultrahigh Performance Short Channel Phototransistor

Two-dimensional (2D) layered materials with properties such as a large surface-to-volume ratio, strong light interaction, and transparency are expected to be used in future optoelectronic applications. Many studies have focused on ways to increase absorption of 2D-layered materials for use in photodetectors. In this work, we demonstrate another strategy for improving photodetector performance using a graphene/MoS₂ heterojunction phototransistor with a short channel length and a tunable Schottky barrier. The channel length of sub-30 nm, shorter than the diffusion length, decreases carrier recombination and carrier transit time in the channel and improves phototransistor performance. Furthermore, our graphene/MoS₂ heterojunction phototransistor employed a tunable Schottky barrier that is only controlled by light and gate bias. It maintains a low dark current and an increased photocurrent. As a result, our graphene/MoS₂ heterojunction phototransistor showed ultrahigh responsivity and detectivity of 2.2 × 10⁵ A/W and 3.5 × 10¹³ Jones, respectively. This is a considerable improvement compared to previous pristine MoS₂ phototransistors. We confirmed an effective method to develop phototransistors based on 2D materials and obtained ultrahigh performance of our phototransistor, which is promising for high-performance optoelectronic applications.

UV-Epoxy-Enabled Simultaneous Intact Transfer and Highly Efficient Doping for Roll-to-Roll Production of High-Performance Graphene Films

Flexible graphene transparent conductive films (TCFs) prepared by chemical vapor deposition hold great promise for next-generation wearable optoelectronic devices, but the lack of low-cost scalable intact transfer and highly efficient doping greatly limits their commercialization. Here, we report a UV-epoxy adhesive as a robust multifunctional layer for the low-cost scalable production of high-performance flexible graphene TCF. Its high solvent stability, sufficient adhesion force, and conformal contact with graphene enable the intact bubbling transfer of graphene. More importantly, a highly strong and stable p-dopant, superacid HSbF₆, is in situ generated from UV-epoxy. HSbF₆ substantially increases the hole concentration of pristine graphene by more than 10 times and consequently reduces its sheet resistance by up to 95% with high stability. Furthermore, it can be readily integrated with the roll-to-roll transfer process. These features enable continuous production of graphene TCFs with overall performances superior to those produced by common transfer methods and typical dopants. As an example, we demonstrate the use of this film in the capacitive multitouch panel of tablet computers.

Self-Aligned Multichannel Graphene Nanoribbon Transistor Arrays Fabricated at Wafer Scale

We present a novel method for fabricating large-area field-effect transistors (FETs) based on densely packed multichannel graphene nanoribbon (GNR) arrays using advanced direct self-assembly (DSA) nanolithography. The design of our strategy focused on the efficient integration of the FET channel and using fab-compatible processes such as thermal annealing and chemical vapor deposition. We achieved linearly stacked DSA nanopattern arrays with sub-10 nm half-pitch critical dimensions (CD) by controlling the thickness of topographic Au confinement patterns. Excellent roughness values (∼10% of CD) were obtained, demonstrating the feasibility of integrating sub-10 nm GNRs into commercial semiconductor processes. Based on this facile process, FETs with such densely packed multichannel GNR arrays were successfully fabricated on 6 in. silicon wafers. With these high-quality GNR arrays, we achieved FETs showing the highest performance reported to date (an on-to-off ratio larger than 10(2)) for similar devices produced using conventional photolithography and block-copolymer lithography.

Substrate-dependent resistance decrease of graphene by ultraviolet-ozone charge doping

Graphene's resistance can decrease as much as 80% via UVO treatment depending on a substrates' band gap and photogenerated charge carriers.

Large-area functionalized CVD graphene for work function matched transparent electrodes

The efficiency of flexible photovoltaic and organic light emitting devices is heavily dependent on the availability of flexible and transparent conductors with at least a similar workfunction to that of Indium Tin Oxide. Here we present the first study of the work function of large area (up to 9 cm(2)) FeCl3 intercalated graphene grown by chemical vapour deposition on Nickel, and demonstrate values as large as 5.1 eV. Upon intercalation, a charge density per graphene layer of 5 ⋅ 10(13) ± 5 ⋅ 10(12) cm(-2) is attained, making this material an attractive platform for the study of plasmonic excitations in the infrared wavelength spectrum of interest to the telecommunication industry. Finally, we demonstrate the potential of this material for flexible electronics in a transparent circuit on a polyethylene naphthalate substrate.