(Invited) All-Chemical Vapor Deposited Graphene/Silicon Nitride TFTs

Abstract

All-chemical vapor deposited silicon nitride / monolayer graphene TFTs have been fabricated. Polychromatic Raman spectroscopy shows high quality monolayer graphene channels with uniform coverage and significant interfacial doping at the source-drain contacts. Nominal mobilities of approximately 1900 cm 2 V -1 s -1 have been measured opening up a potentially useful platform for analogue and RFR-based applications fabricated through allchemical vapor deposition processes.Graphene is a one atomic thick layer of carbon atoms, where their sp 2 bonds are arranged in a honeycomb crystal lattice. It is being touted as the new "miracle material" for electronics and photonics in the 21 st Century. This is because of its unique properties such as the very high carrier mobility at room temperature, large free mean path for ballistic transport, high Young's modulus and near zero-gap semiconductor (semi-metal). These make it potentially unique for nano-electronics, biosensors and information and computer technologies. Early graphene transistor configurations consisted of back-gated metal-oxide-semiconductor field effect transistors. Alternative top-gate configurations include the use of channels formed from high-quality natural and Kish exfoliated graphene, CVD grown and polymer transferred graphene and epitaxial deposited samples. SiO 2 , Al 2 O 3 , and HfO 2 have been investigated as viable dielectrics in zero band gap devices. Graphene transistors exhibit linear transfer characteristics without saturation or weakly saturate followed by a secondary linear regime [1]. Due to the low on/off current ratio, graphene-based devices are unsuitable for logic applications through various routes to bandgap opening have been proposed, such as the use of sub-5 nm-wide nanoribbons [2], mechanically strained free-standing channels, and biased bilayers [3].The dielectric is known to affect the charge carrier type in graphene devices [4]. SiN x has been successfully used as a dielectric for TFTs within flat-panel displays for many years, yielding a mature and widely accepted technology, which is, for example, routinely used in a-Si backplanes for organic light-emitting diode displays [5]. In this work, we show TFTs based on monolayer graphene as the active channel material with SiN x as the insulator where both materials have been produced using chemical vapor deposition (CVD) processes. Though low on/off ratios mitigate against their use in logic circuits they are well suited for analog RF applications, in body area networks and some flat panel applications.Bottom gated graphene TFTs were produced on 300 nm thick SiN dielectric layers deposited by PECVD onto degenerately doped silicon substrates. SiN x was deposited at 150 o C using radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) 10.1149/05008.0217ecst ©The Electrochemical Society ECS Transactions, 50 (8) 217-221 (2012) 217 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.59.222.12 Downlo...

Morphology and Magneto‐Transport in Exfoliated Graphene on Ultrathin Crystalline β‐Si3N4(0001)/Si(111)

“…In fact, similar effects were already observed for graphene on SiO 2 [ 58,59 ] and on SiN x . [ 21 ]…”

“…Examples of graphene/silicon nitride interfaces, mainly in view of device fabrication, were already reported, [ 11,21–24 ] but the methods employed for interface fabrication relied on nitride growth on top of the graphene layer [ 11,22 ] or on high‐temperature graphene growth on top of nitride surfaces. [ 23,24 ] In both cases, the resulting silicon nitride layer is amorphous or polycrystalline and must be thick, in order to preserve its insulating properties.…”