Oxygen vacancies modulating self-powered photoresponse in PEDOT:PSS/ε-Ga2O3 heterojunction by trapping effect

• Published in: Science China. Technological sciences 2022-03, Vol.65 (3), p.704-712
• Main Authors: Li, Shan, Yue, JianYing, Lu, Chao, Yan, ZuYong, Liu, Zeng, Li, PeiGang, Guo, DaoYou, Wu, ZhenPing, Guo, YuFeng, Tang, WeiHua
• Format: Article
• Language: English
• Subjects: Annealing; Charge transfer; Current carriers; Dark current; Decay rate; Defects; Engineering; Gallium oxides; Heterojunctions; Modulation; Quantum efficiency; Trapping; Vacancies
• ISSN: 1674-7321; 1869-1900
• DOI: 10.1007/s11431-021-1945-x

Can the modulation effect of charge-carrier transfer be inherited from a single layer to its heterojunction structure? Certainly, the answer is yes. Herein, we experimentally verify that the photodetection performance modulation effect of oxygen vacancy ( V o ) is transmitted from the ε -Ga 2 O 3 layer to the PEDOT:PSS/ ε -Ga 2 O 3 (PGO) hybrid heterojunction. By adopting the annealed ε -Ga 2 O 3 films, whose V o concentrations are remolded by annealing ambients, the constructed PGO photodetectors (PDs) demonstrate regulable self-powered performance. As the V o defects decrease, the photodetection properties are effectively enhanced with a high photo-to-dark current ratio of 2.37×10 7 , an excellent on/off switching ratio of 6.45×10 5 , fast rise/decay time of 121/72 ms, a large responsivity of 67.9 mA/W, superior detectivity of 9.2×10 13 Jones, an outstanding external quantum efficiency of 33.2%, and a high rejection ratio ( R 250 / R 400 ) of 5.96×10 6 at 0 V in PGO-O 2 PD. The better photoresponse is attributed to the less V o defect concentration in the ε -Ga 2 O 3 layer, which could favor the lower electron-trapping probability and a more efficient charge-carrier transfer. Considering the universality of V o defects in oxide materials, the proposed regulation strategy of photoresponse will open the route of high self-powered performance for next-generation ultraviolet PDs.