文章基本信息

标题：Gap state analysis in electric-field-induced band gap for bilayer graphene
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作者：Kaoru Kanayama ; Kosuke Nagashio
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2015
卷号：5
DOI：10.1038/srep15789
出版社：Springer Nature
摘要：The origin of the low current on/off ratio at room temperature in dual-gated bilayer graphene field-effect transistors is considered to be the variable range hopping in gap states. However, the quantitative estimation of gap states has not been conducted. Here, we report the systematic estimation of the energy gap by both quantum capacitance and transport measurements and the density of states for gap states by the conductance method. An energy gap of ~250 meV is obtained at the maximum displacement field of ~3.1 V/nm, where the current on/off ratio of ~3 × 10³ is demonstrated at 20 K. The density of states for the gap states are in the range from the latter half of 10¹² to 10¹³ eV⁻¹cm⁻². Although the large amount of gap states at the interface of high- k oxide/bilayer graphene limits the current on/off ratio at present, our results suggest that the reduction of gap states below ~10¹¹ eV⁻¹cm⁻² by continual improvement of the gate stack makes bilayer graphene a promising candidate for future nanoelectronic device applications.