Division of Materials Science and Engineering , Hanyang University , Seoul 04763 , Republic of Korea.
ACS Appl Mater Interfaces. 2018 Apr 25;10(16):14170-14174. doi: 10.1021/acsami.8b02043. Epub 2018 Apr 16.
Graphene has attracted great attention as an alternative to conventional metallic or transparent conducting electrodes. Despite its similarities with conventional electrodes, recent studies have shown that a single-atom layer of graphene possesses unique characteristics, such as a tunable work function and transparencies for electric potential, reactivity, and wetting. Nevertheless, a systematic analysis of graphene and semiconductor junction characteristics has not yet been carried out. Here, we report the photoresponse characteristics of graphene-on-GaN Schottky junction photodiodes (Gr-GaN SJPDs), showing a typical rectifying behavior and distinct photovoltaic and photoelectric responses. Following the initial abrupt response to UV illumination, the Gr-GaN SJPDs exhibited a distinct difference in photocarrier dynamics depending on the applied bias voltage, which is characterized by either a negative or positive change in photocurrent with time. We propose underlying mechanisms for the anomalous photocarrier dynamics based on the interplay between electrostatic molecular interactions over the one-atom-thick graphene and GaN junction and trapped photocarriers at the defect states in the GaN thin film.
石墨烯作为传统金属或透明导电电极的替代品引起了极大的关注。尽管它与传统电极有相似之处，但最近的研究表明，单层石墨烯具有独特的特性，例如可调谐的功函数和对电势、反应性和润湿性的透明度。然而，对石墨烯和半导体结特性的系统分析尚未进行。在这里，我们报告了石墨烯/氮化镓肖特基结光电二极管 (Gr-GaN SJPD) 的光响应特性，其表现出典型的整流行为以及明显的光伏和光电响应。在对紫外光照射的初始急剧响应之后，Gr-GaN SJPD 的光载流子动力学根据施加的偏置电压表现出明显的差异，其特征是光电流随时间呈负或正变化。我们基于在一个原子层厚的石墨烯和 GaN 结上的静电分子相互作用以及在 GaN 薄膜中的缺陷态中俘获的光载流子之间的相互作用，提出了反常光载流子动力学的潜在机制。
