基於氮化鋁鎵和石墨烯-氮化硼異質結構之新穎太陽隱蔽深紫外光感測器

Abstract

隨著科技的發展，紫外光感測器因其在光譜上的專一性而能在諸多領域有所應用，從殺菌、水質淨化到光通訊。由於傳統的矽基紫外光感測器因其狹窄能隙而有明顯的缺陷，擁有寬能隙的半導體，也就是能隙超過4電子伏特的材料，便成為矽絕佳的替代品。在此研究中，透過組合各個部件材料的特性，我們設計出一種由石墨烯-數層六方晶氮化硼-n型氮化鋁鎵構成且擁有良好性能的新型太陽盲區深紫外光感測器。在元件中作為寬能隙半導體之一的氮化鋁鎵讓元件能在不需要紫外光過濾片的情況下就能偵測深紫外訊號而不受可見光等的影響，因此使元件是真正的太陽盲光感測器。此外，石墨烯-六方晶氮化硼異質接面用來解決石墨烯與傳統塊材絕緣體接面之間的應變導致的問題，以此提升元件的表現。另外，石墨烯對紫外光擁有極高穿透率，這讓入射光能在極少能量損失下直接激發主動層中的載子。二維六方晶氮化硼絕緣層則能抑制漏電流並協助光載子進行量子穿隧。有趣的是，相較於已經發表以氮化鋁鎵為基礎的深紫外光感測器，此研究所提出的光感測器能在不施加高額外加偏壓下便擁有優良的響應度和偵測率。

Nowdays, the deep-ultraviolet photodetectors are useful in the progression of many fields, extending from disinfection, water purification to optical communication due to their spectral specificity. Because of the fact that silicon-based devices possess obvious flaws in ultraviolet devices owing to its narrow band gap, thus wide-bandgap semiconductors, which have band gap exceeding 4 eV, provide excellent alternatives. In this study, through the combination of the characteristics of each component material, we design a nanolayered graphene/hBN/n-AlGaN deep-ultraviolet and solar-blind photodetector with high performance. The AlGaN, which belongs to wide-bandgap materials, enables the device to sense deep-ultraviolet signals without the need of ultraviolet-pass filter and hence makes the device be a true solar-blind photodetector. Besides, the several nanolayered graphene-hBN heterostructure is employed to enhance the device performance, which successfully solves the strain emerged between the graphene and conventional bulk insulators. Furthermore, the high transparency of graphene can cause incident signals to directly excite the carriers in active layer with negligible energy loss, and the two-dimensional hBN insulating layer is beneficial to suppress leakage current and aid quantum tunneling of photogenerated carriers. Interestingly, the photodetectors presented in this study show favorable responsivity and detectivity without the requirement of high external bias compared with published AlGaN-based deep-ultraviolet photodetectors.