Graphene Interdigital Electrodes for Improving Sensitivity in a Ga₂O₃:Zn Deep-Ultraviolet Photoconductive Detector

Graphene (Gr) has been widely used as a transparent electrode material for photodetectors because of its high conductivity and high transmittance in recent years. However, the current low-efficiency manipulation of Gr has hindered the arraying and practical use of such detectors. We invented a multistep method of accurately tailoring graphene into interdigital electrodes for fabricating a sensitive, stable deep-ultraviolet photodetector based on Zn-doped Ga₂O₃ films. The fabricated photodetector exhibits a series of excellent performance, including extremely low dark current (∼10⁻¹¹ A), an ultrahigh photo-to-dark ratio (>10⁵), satisfactory responsivity (1.05 A/W), and excellent selectivity for the deep-ultraviolet band, compared to those with ordinary metal electrodes. The raise of photocurrent and responsivity is attributed to the increase of incident photons through Gr and separated carriers caused by the built-in electric field formed at the interface of Gr and Ga₂O₃:Zn films. The proposed ideas and methods of tailoring Gr can not only improve the performance of devices but more importantly contribute to the practical development of graphene.