Hossain Md Zakir, Kosei Ogawa
Gunma University Initiative for Advanced Research (GIAR), Gunma University, Kiryu 376-0023, Japan.
Department of Chemistry and Molecular Biology, Gunma University, Kiryu 376-8515, Japan.
ACS Omega. 2024 Jul 18;9(30):32942-32948. doi: 10.1021/acsomega.4c03882. eCollection 2024 Jul 30.
Because of their tunable band gap, flexibility, and high surface-to-volume ratio, two-dimensional materials have appeared as the most promising materials for ultraviolet (UV) light sensors. Here, we report the detection of UV light by oxidized epitaxial graphene (EG) formed on the Si-face of the SiC substrate and graphene oxide (GO) produced by Hummer oxidation of graphite. Both epitaxial graphene oxide (EGO) and GO were characterized by Raman and X-ray photoelectron spectroscopy, and the devices were made simply by placing two parallel copper electrodes onto the graphene oxide layers. Irradiation of UV light onto the graphene oxides was realized by the real-time current measurements between two electrodes at a fixed bias of 1 V. The sudden upward jump of the current (Ids) upon UV light irradiation was observed in both EGO- and GO-based devices, which were returned to the original value, while the UV source was turned OFF. The photocurrent ( ), the magnitude of the current jump by the UV irradiation, for EGO, was estimated at 8 mA with a channel distance of 2 mm and UV power of 80 mW/cm. The linearly increases with UV power. In the case of GO, was estimated at 0.2 nA with a similar setup. The photoresponse time and responsivity for EGO are ∼11 s and 5.6 A/W, respectively, which are higher than those of GO. The quantum efficiencies (η) for EGO and GO are calculated as 1907 and 2.3 × 10 %, respectively, with an incident power of UV light at 9 mW/cm. Because of the advantages of the EG on SiC concerning the stability and wafer scale growth, the present study is expected to lead the development of lab-on-chip-based ultrasensitive UV sensors.
由于其可调谐的带隙、柔韧性和高表面积与体积比，二维材料已成为用于紫外（UV）光传感器的最有前途的材料。在此，我们报告了通过在SiC衬底的Si面上形成的氧化外延石墨烯（EG）和通过石墨的Hummer氧化制备的氧化石墨烯（GO）来检测紫外光。外延氧化石墨烯（EGO）和GO均通过拉曼光谱和X射线光电子能谱进行表征，并且这些器件只需将两个平行的铜电极放置在氧化石墨烯层上即可制成。通过在1 V的固定偏压下测量两个电极之间的实时电流来实现对氧化石墨烯的紫外光照射。在基于EGO和GO的器件中均观察到紫外光照射时电流（Ids）突然向上跃升，当紫外光源关闭时，电流又恢复到原始值。对于EGO，光电流（即紫外照射引起的电流跃升幅度）在通道距离为2 mm且紫外功率为80 mW/cm²时估计为8 mA。光电流随紫外功率线性增加。在GO的情况下，在类似设置下光电流估计为0.2 nA。EGO的光响应时间和响应度分别约为11 s和5.6 A/W，高于GO。在紫外光入射功率为9 mW/cm²时，EGO和GO的量子效率（η）分别计算为1907和2.3×10⁻⁴%。由于SiC上的EG在稳定性和晶圆级生长方面的优势，本研究有望引领基于芯片实验室的超灵敏紫外传感器的发展。
