講演情報
[17p-M_101-15]Suspended Graphene Photodetector with asymmetric Metal contacts
〇(M2)Yiwei Yang1, Ryota Seki1, Rei Shuto1, Isao Morohashi2, Ya Zhang1 (1.Institute of Engineering, Tokyo University of Agriculture and Technology, 2.National Institute of Information and Communications Technology)
キーワード：
Graphene、Metal contacts、Suspended structure
Graphene-based photodetectors employing dissimilar metal electrodes have attracted considerable interest due to their potential for enhanced performance. Since achieving stable and controllable doping in graphene remains challenging, metals with different work functions are utilized to locally induce p-type and n-type doping in graphene near the respective contacts, thereby forming a pn-like junction structure. This asymmetric contact-induced doping generates an internal built-in electric field, which facilitates efficient separation of photogenerated carriers and leads to a photovoltaic response.Owing to the difference in metal work functions, distinct doping levels are introduced in graphene at the two contacts. As a result, the device exhibits asymmetric and nonlinear current–voltage (I–V) characteristics under opposite bias polarities, originating from polarity-dependent field-induced tunneling processes at the metal–graphene interfaces. Furthermore, the suspended graphene architecture suppresses substrate-induced scattering and thermal dissipation, allowing interface-dominated transport behavior to be more clearly observed.In this work, we demonstrate a suspended graphene photodetector with asymmetric metal contacts, in which gold (Au) and aluminum (Al) are employed as the contact metals. The tunneling current density at each metal–graphene junction under applied bias is calculated based on the Bardeen transfer Hamiltonian (BTH) model, and the overall device response is obtained by superposing the contributions from the two junctions. The experimentally measured I–V characteristics show good agreement with the calculated results, with both exhibiting pronounced bias-dependent asymmetry and nonlinearity. In addition, the formation of the suspended structure through hydrofluoric acid etching results in a significant reduction in device resistance, decreasing from approximately 19 kΩ to 430 Ω.