期刊
ACS APPLIED MATERIALS & INTERFACES
卷 8, 期 1, 页码 834-839出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.5b10183
关键词
graphene; graphene mesh; electrolyte-gated field effect transistor; pH sensor; nanosensor; defect-mediated chemisorption; defect passivation
资金
- Basic Science Research Program [2015R1A2A2A11001426]
- International Research & Development Program of the National Research Foundation of Korea (NRF) - Ministry of Science, ICT and Future Planning (MSIP) of Korea [2013K1A3A1A32035393]
- Air Force Office of Scientific Research/Asian Office of Aerospace Research Development (AFOSR/AOARD) through the Nano Bio Info Technology (NBIT) Phase III Program [AOARD-13-4125]
- National Research Foundation of Korea [2013K1A3A1A32035393] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
We have studied the role of defects in electrolyte-gated graphene mesh (GM) field-effect transistors (FETs) by introducing engineered edge defects in graphene (Gr) channels. Compared with Gr-FETs, GM-FETs were characterized as having large increments of Dirac point shift (similar to 30-100 mV/pH) that even sometimes exceeded the Nernst limit (59 mV/pH) by means of electrostatic gating of H+ ions. This feature was attributed to the defect-mediated chemisorptions of H+ ions to the graphene edge, as supported by Raman measurements and observed cycling characteristics of the GM FETs. Although the H+ ion binding to the defects increased the device response to pH change, this binding was found to be irreversible. However, the irreversible component showed relatively fast decay, almost disappearing after 5 cycles of exposure to solutions of decreasing pH value from 8.25 to 6.55. Similar behavior could be found in the Gr-FET, but the irreversible component of the response was much smaller. Finally, after complete passivation of the defects, both Gr-FETs and GM-FETs exhibited only reversible response to pH change, with similar magnitude in the range of 68 mV/pH.
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