Supercapacity (>1000 μf/cm2) charge release in a CVD-grown WSe2 FET incorporating a PEO: CsCIO4 side gate

M. Asghari Heidarlou, B. Jariwala, P. Paletti, S. Rouvimov, J. A. Robinsorr, S. K. Fullerton-Shirey, A. Seabaugh

Research output: Chapter in Book/Report/Conference proceedingConference contribution


We report extraordinarily high capacitance density in tungsten diselenide (WSe2) field-effect transistors (FETs) capped with polyethylene oxide (PEO) and ion doped with cesium perchlorate (CsCIO4). The FETs have 3-4 monolayer WSe2 channels grown by chemical vapor deposition (CVD) using W(CO)6 and H2Se at 800 °C for 30 minutes [1]. A stepper-based process was used to fabricate the transistors and an 11 nm Al2O3 atomic layer deposited (ALD) gate dielectric was formed on the WSe2 with a low temperature nucleation layer, 1 nm Ah03, deposited at 110 °C to facilitate nucleation followed by a 10 nm Ah03 deposited at 200 °C, after Kwak [2]. The n-FET achieves an ON/OFF ratio of 106 with noise-floor-limited gate current. Most prior studies of WSe2 FETs have been on exfoliated materials and to our knowledge there is only one prior report of a top-gated CVD WSe2 p-FET [3]. Following FET characterization PEO: CsCIO4 was drop-cast and annealed at 90 °C for 3 minutes in Ar after Xu [4], yielding a layer thickness of 400 nm as measured by transmission electron microscopy (TEM). Ion gating using a side gate (6μm from the WSe2 mesa edge) produces ambipolar transfer characteristics with approximately equal ON-currents of 2μ A/μm attributed to the multi-work-function source/drain contacts [5]. ON/OFF current ratio exceeds 106 with field-effect electron and hole mobilities of 10 and 25 cm2/Vs respectively and subthreshold swings of 260 and 180 mY/decade respectively. Atomic force microscope images show that the WSe2 nucleates in triangles which are apparent in Fig. 1; FET characteristics after testing of the transistor are shown in Fig. 2 along with TEM.

Original languageEnglish (US)
Title of host publication2018 76th Device Research Conference, DRC 2018
PublisherInstitute of Electrical and Electronics Engineers Inc.
ISBN (Print)9781538630280
StatePublished - Aug 20 2018
Event76th Device Research Conference, DRC 2018 - Santa Barbara, United States
Duration: Jun 24 2018Jun 27 2018

Publication series

NameDevice Research Conference - Conference Digest, DRC
ISSN (Print)1548-3770


Other76th Device Research Conference, DRC 2018
Country/TerritoryUnited States
CitySanta Barbara

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering


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