基于碳化硅外延石墨烯的紫外/红外双色探测器研究

Ultraviolet (UV) / infrared (IR) dual-color photodetectors have attracted more and more attention because of their high sensitivity and low false alarm rate. Up to now, kinds of UV/IR dual-color detectors have been reported. However, the low temperature limitation, unstable and toxicity made these kinds of detectors not meet the requirement of practical applications. To solve these problems, the new material should be developed for new generation of practical UV/IR dual-color photodetector. Here, the patterned epitaxial graphene (EG) on silicon carbide (SiC) is suggested as the basic material to fabricate the UV/IR dual-color photodetector. The SiC substrate with the bandgap of 3-3.2eV can detect UV light. When the EG is patterned into arrays with nanoscale size, it can be used as IR detector. Therefore, the EG on SiC can detect UV and IR light at the same time. The growth of layer controllable EG is important for the analysis of the relationship between the layer number and the property of the detector. The size and the shape, especially the edge spin states from different shape of patterned graphene, are the key factors for the IR adsorption of graphene plasmon. And the physical principle will be studied. In addition, the interface property between EG and SiC substrate might be critical for both the UV and IR detecting. Also the physical origin will be explored. As optimation with the top gate and the PIN structure of SiC used, the prototype device of UV/IR dual-color photodetector will be obtained, which will provide the fundamental theories and experiments for the further development of UV/IR dual-color photodetector.

紫外/红外双色光电探测器具有高响应度、低虚警率的优势，成为光电探测领域的新星，受到了国际和国内的广泛关注。但是，到目前为止，已有的双色探测器存在稳定性差、可控性差、只适用于低温环境等固有缺点，因此发展可靠实用的新型双色探测器成为现阶段的研究重点。本项目结合图形化石墨烯的等离子体增强红外响应特性和碳化硅的本征紫外响应特性，创新提出以图形化碳化硅外延石墨烯为基础，制备紫外/红外双色光电探测器。重点研究不同碳化硅晶面上石墨稀生长机理，实现对石墨稀层数等特性的调控；探索石墨烯边界状态对红外探测性能的影响规律，建立不同边界自旋态石墨烯的等离子体对红外光谱的吸收模型；探究不同石墨烯/碳化硅界面间作用力对紫外和红外探测性能影响的物理机制与协同增强机理。在此基础上，优化器件工艺以获得紫外/红外双色探测器原型器件，为紫外/红外双色光电探测器领域的发展提供新思路，推动双色探测器的应用步伐。

紫外/红外双色探测器能够有效拓展探测器的波长范围，实现高响应度和低虚警率，成为近几年国内外光电探测领域的研究热点。但是，由于现阶段的紫外/红外双色探测器尚处于起步阶段，现有材料体系少、需要低温冷却、稳定性不好、含有毒性材料。因此，急需提出新型双色探测器结构。本项目提出石墨烯/碳化硅双色探测器，利用石墨烯的红外吸收性能和碳化硅的紫外吸收性能，实现室温下双色探测。项目针对高质量石墨烯材料的制备、石墨烯/碳化硅异质结界面物理性能及双色探测器研制三方面展开。首先，设计新型石墨烯生长系统，通过调控Si原子逸出速度，实现石墨烯生长调控，获得大面积高质量石墨烯和区域分散生长石墨烯。其次，针对石墨烯/碳化硅异质结界面光生载流子输运行为，创新提出紫外光辅助开尔文探针力显微镜（UV-KPFM）表征方法，从实验上直接观测到石墨烯/碳化硅界面处紫外光照下的载流子输运行为，阐明碳化硅晶面类型和表面态浓度对界面能带分布和能态密度的影响机制。并将UV-KPFM表征方法成功拓展到GaN、金属等离激元等多种材料体系的光电性能表征，为电子器件、光电子器件中电荷输运表征提供了有效的表征手段。利用石墨烯/碳化硅界面内建电场效应，实现Ti/石墨烯/碳化硅欧姆接触，Ni/石墨烯/碳化硅肖特基接触。通过内建电场驱动与能态密度限域的平衡作用，实现外电场驱动下的响应度调控。基于此高均匀性石墨烯电极制备1cm×1cm大灵敏面积自驱动紫外探测，实现278nm波段响应度为0.2A/W，响应速度5us。并结合石墨烯纳米片层的高红外吸收特性，实现针对红外980nm和紫外266nm的紫外/红外双色探测器。为紫外/红外双色光电探测器领域的发展提供新思路。项目执行期发表论文5篇，授权发明专利1项，申请发明专利4项，参加国际会议1次，国内会议2次。项目负责人荣获吉林省科学技术奖自然科学一等奖（第7完成人），入选中国科学院青促会，并晋职为副研究员。