Non-volatile Capacitance Tuning in Graphene/(Hf,Zr)O/Metal Varactors

V. R. Saran Kumar Chaganti, Yao Zhang, Steven J. Koester

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


Two-dimensional graphene-based devices which utilize the tunable quantum capacitance property in graphene have been studied for a number of sensing and optical applications [1]-[3]. Radio frequency (RF) variable capacitors (varactors) can be realized in the form of metal-oxide-graphene structures [4] by exploiting the high carrier mobility and the above-stated tunable capacitance property in graphene. High-speed graphene varactors could have potential for use in beam-steering antennas and other communication devices, particularly those requiring glass or flexible substrates where integration of tuning elements would otherwise require flip-chip bonding of bulky tuning elements [5]. While conventional graphene varactors can potentially address the critical need for RF-compatible tunable elements [6], they would still need a power supply during operation. In this work, we report for the first time, graphene varactors integrated with ferroelectric (Hf,Zr)O (HZO). The devices display capacitance tuning ratio of 1.5 within a \pm 2\mathrm{V} gate voltage sweep, with Dirac point (V-{\mathrm{Dirac}}) tunability of 1.7 V within the same sweep window. Furthermore a non-volatile (zero-bias) tuning ratio of 1.2 was achieved, with significant further improvement possible through design optimization. These results could have important significance in a wide range of reconfigurable RF communication applications including wearable antennas, and autonomous vehicles.

Original languageEnglish (US)
Title of host publication2019 Device Research Conference, DRC 2019
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages2
ISBN (Electronic)9781728121123
StatePublished - Jun 2019
Event2019 Device Research Conference, DRC 2019 - Ann Arbor, United States
Duration: Jun 23 2019Jun 26 2019

Publication series

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


Conference2019 Device Research Conference, DRC 2019
Country/TerritoryUnited States
CityAnn Arbor

Bibliographical note

Publisher Copyright:
© 2019 IEEE.


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