[15a-B6-1~11] 17.2 グラフェン

[15a-B6-2] 単一狭窄構造グラフェンナノリボンにおける単キャリアトランジスター操作の研究

〇(M2)WANG Zhongwang¹、岩崎 拓哉¹、ムルガナタン マノハラン¹、水田 博¹ (1.北陸先端大)

キーワード：グラフェン、単キャリアトランジスター

The random charge localization caused by defects, and edge roughness in graphene nanoribbons heavily influences the electrical characteristics for graphene based single carrier transistors (SCTs) devices. However, with the current top-down process technique, it is difficult to achieve a perfect graphene edge, which limits the graphene SCT performance. In order to overcome this issue, the total edge length of graphene SCTs narrower part has to be reduced. In this direction, a single constriction of a few tens of nanometer in which enables to realize the SCT operation with the quantized energy levels. The total edge length of this structure is shorter compared to the geometrically defined quantum dot structure. Moreover, graphene surface should be protected from external adsorbents to avoid spurious interaction. For this purpose, we have coated the top graphene surface with Hydrogen silsesquioxane (HSQ) resist. It is converted into SiO₂ by exposing with the electron beam. Narrow single constrictions with different width (W) and length (L) connected to two wide leads were patterned by using electron beam lithography technique followed by an O₂ plasma etching. Then gold electrodes were attached on the top of the graphene leads. The Id-Vg modulation in devices with different L and W were measured. Compared to the devices with widths wider than 70 nm, devices those with narrower widths show more pronounced the coulomb oscillation superimposed onto the graphene ambipolar characteristics. The coulomb diamond was observed for a device with W₁= ~ 40 nm and length L=100 nm. Although the noise from edge roughness still exists, coulomb diamonds were obtained which describing SCT characteristics. The detailed analysis will be presented in the conference.