利用二氧化钛薄膜光吸收及表面钝化特性, 在硅晶圆基底表面制备石墨烯/二氧化钛异质结场效应管光电探测器, 并研究其光电响应特性.结果表明, 二氧化钛钝化后的探测器可以有效抑制沟道表面的气体小分子吸附, 降低器件的暗电流漂移; 同时, 探测器利用石墨烯的电荷敏感和复合薄膜的光谱吸收特性, 显著提高了石墨烯场效应管的响应度.紫外波段, 顶层二氧化钛吸光产生的光生电子将注入到石墨烯沟道中, 对石墨烯沟道产生n型掺杂, 器件最大响应度可达3.5×105 A/W.在可见光波段, 因为二氧化钛层与石墨烯薄膜间存在杂质能级, 界面间的电荷转移使沟道载流子寿命显著提高.相对于传统的二氧化钛阵列探测器, 该探测器在响应波段与响应度性能上都具有明显优势.

The photodetector based on Graphene/TiO2 heterostructure is fabricated on the substrate of Si wafer, which takes advantage of the light absorption and surface passivation of TiO2 film. The intrinsic photo-response of the photodetector is investigated in a wide range of wavelength. The result indicates that the graphene field-effect transistor photodetectors passivated with TiO2 film deposited on graphene can efficiently prevent the surface channel absorbing the gas molecules, which reduces the dark current drift of graphene field-effect transistor devices. Meanwhile, the graphene channel is sensitive to the changes in charge, and wide spectral absorption characteristics of the composite film can increase the responsivity of graphene field-effect transistor detector significantly. At the ultraviolet band, the photon-generated carries produced by TiO2 layer are mostly injected into the graphene channel, which leads to obvious n-type doping and the highest responsibility of 3.5×105 A/W. On the other side, at the visible band the impurity level between graphene and TiO2 can improve the carrier lifetime of channel compared with the intrinsic graphene. In contrast with the traditional TiO2 arrays photodetectors, the Graphene/TiO2 heterostructure devices have obvious advantage on the performance of response waveband and responsibility.