Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 11, Issue 12, Pages 12170-12178Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.9b02400
Keywords
graphene; field effect transistor; photoelectric field-induced doping; proton-hopping; silicon dioxide
Funding
- National Natural Science Foundation of China [61671368, 61172041, 91123018, 61404103]
- Science and Technology on Analog Integrated Circuit Laboratory [614280205040617]
- Science and Technology Planning Project of Guangdong Province, China [2017A010103004]
- Basic Public Welfare Research Planning Project of Zhejiang Province [LGG19F040002]
- Fundamental Research Funds for the Central Universities
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Photoinduced hysteresis (PIH) of graphene field-effect transistors (G-FETs) has attracted attention because of its potential in developing photoelectronic or nonvolatile memory devices. In this work, we focused on the role of SiO2 dielectric layer on PIH, where G-FETs have only a SiO2 dielectric layer. Adsorbates are effectively removed before the PIH test. The effects of laser wavelength, laser power density, and temperature on the PIH are systematically investigated. The PIH is significantly enhanced by increasing the hydrogen flow in a hydrogen-atmosphere device thermal annealing. This strongly suggests proton-related defects that play a key role. The pure electronic process for PIH is further ruled out by the significant dependence of the doping rate temperature. A mechanism of PIH based on proton generation after hole trapping at [O-3 Si-H] is proposed. The proposed mechanism is well-supported by our experimental data: (1) the observed threshold photon energy for PIH is between 2.76 and 2.34 eV, which is close to the energy barrier for [O-3 Si-H], releasing a proton. (2) No obvious carrier mobility degradation after the PIH process suggests that the bulk defects in SiO2 are the major contributors rather than graphene/SiO2 interface defects. (3) The dependence of the doping rate on the temperature and the laser power density matches a theoretical model based on the random hopping of H+. The results in this work are also valuable for the study of degradation of other oxide dielectric materials in various field-effect transistors.
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