Center for Optoelectronics Materials and Devices, Department of Physics, Zhejiang Sci-Tech University , Hangzhou 310018, China.
State Key Laboratory of Information Photonics and Optical Communications & Laboratory of Optoelectronics Materials and Devices, School of Science, Beijing University of Posts and Telecommunications , Beijing 100876, China.
ACS Appl Mater Interfaces. 2017 Jan 18;9(2):1619-1628. doi: 10.1021/acsami.6b13771. Epub 2017 Jan 6.
A solar-blind photodetector based on β-GaO/NSTO (NSTO = Nb:SrTiO) heterojunctions were fabricated for the first time, and its photoelectric properties were investigated. The device presents a typical positive rectification in the dark, while under 254 nm UV light illumination, it shows a negative rectification, which might be caused by the generation of photoinduced electron-hole pairs in the β-GaO film layer. With zero bias, that is, zero power consumption, the photodetector shows a fast photoresponse time (decay time τ = 0.07 s) and the ratio I/I ≈ 20 under 254 nm light illumination with a light intensity of 45 μW/cm. Such behaviors are attributed to the separation of photogenerated electron-hole pairs driven by the built-in electric field in the depletion region of β-GaO and the NSTO interface, and the subsequent transport toward corresponding electrodes. The photocurrent increases linearly with increasing the light intensity and applied bias, while the response time decreases with the increase of the light intensity. Under -10 V bias and 45 μW/cm of 254 nm light illumination, the photodetector exhibits a responsivity R of 43.31 A/W and an external quantum efficiency of 2.1 × 10 %. The photo-to-electric conversion mechanism in the β-GaO/NSTO heterojunction photodetector is explained in detail by energy band diagrams. The results strongly suggest that a photodetector based on β-GaO thin-film heterojunction structure can be practically used to detect weak solar-blind signals because of its high photoconductive gain.
首次制备了基于β-GaO/NSTO（NSTO=Nb:SrTiO）异质结的太阳盲光电探测器，并研究了其光电性能。该器件在黑暗中呈现典型的正向整流，而在 254nmUV 光照射下，呈现负向整流，这可能是由于β-GaO 薄膜层中光生电子-空穴对的产生。在零偏压下，即零功耗下，光电探测器在 254nm 光照射下表现出快速光响应时间（衰减时间τ=0.07s），光电流比 I/I≈20，光强为 45μW/cm。这种行为归因于光生电子-空穴对在β-GaO 和 NSTO 界面的耗尽区内置电场的驱动下分离，以及随后向相应电极的传输。光电流随光强和外加偏压的增加而线性增加，而响应时间随光强的增加而减小。在-10V 偏压和 45μW/cm 的 254nm 光照射下，光电探测器表现出 43.31A/W 的响应率 R 和 2.1×10%的外量子效率。通过能带图详细解释了β-GaO/NSTO 异质结光电探测器中的光电转换机制。结果强烈表明，基于β-GaO 薄膜异质结结构的光电探测器由于具有较高的光电导增益，可实际用于探测微弱的太阳盲信号。
