Research On Preparation And Performance Of The Photodetector Based On ZnO Nanorods Heterojunction

In recent years,photodetectors have been widely used in various fields,such as military and national economy,so they have great application value and are worthy of scientific attention.In this paper,we fabricated heterojunction photodetectors based on ZnO nanorod arrays by taking advantage of the wide band gap and high electron mobility of ZnO,and excellent photoelectric properties were obtained by doping Ga element into ZnO nanorods(ZnO NRs).Firstly,we assembled a self-powered ultraviolet photodetector based on n-ZnO NRs/p-GaN heterojunction,in which the ZnO NRs were prepared by water bath method.However,the ZnO NRs made by water bath method contain many defects,and that defects capture photogenerated carriers will result in a decreased photoelectric performance of photodetectors.Thus the Ga element was doped into ZnO nanorods to reduce defect concentration of nanorods,which may benefit improving the detection performance.In this research,we found that the Ga:ZnO NRs(GZO NRs)/GaN heterojunction detectors not only had better photoelectric response compared with ZnO NRs/GaN detectors,but also achieved a more reliable self-powered performance.Under the 1.31 mW/cm2 hybrid ultraviolet irradiation,the Iph/Idark ratio of GZO NRs/GaN detector was up to 3.2×105 at zero bias,which was 75 times lager than that of the ZnO NRs/GaN heterojunction.Furthermore,its maximum responsivity was as high as 0.23 A/W,over 3 times the value of device with undoped ZnO NRs(UZO NRs).Secondly,we successfully prepared another self-powered photodetector based on GZO NRs/CH3NH3PbI3/MoO3 heterojunction,in which the ZnO NRs were served as scaffold and CH3NH3PbI3 perovskite film was prepared by traditional two-step solution method.The CH3NH3PbI3 based photodetectors had a broad response spectra ranging from 300 nm to 800 nm due to the wide absorption band of perovskite.Comparing the GZO NRs/CH3NH3PbI3/MoO3 and ZnO NRs/CH3NH3PbI3/MoO3 photodetectors,the responsivity and detectivity maximum values of GZO NRs/CH3NH3PbI3/MoO3 photodetectors,which reached about 0.34 A/W and 1.6×1012 Jones respectively,were higher than those of ZnO NRs/CH3NH3PbI3/MoO3 photodetectors.It revealed that the Ga-doped ZnO nanorod scaffold had potential to optimize self-powered detection performance of perovskite detectors.In order to simplify the structure of GZO NRs/CH3NH3PbI3/MoO3 photodetectors ulteriorly,we prepared a perovskite photodetector without hole transmission layer.By preparing graphite electrode on GZO NRs/perovskite,the photodetector based on GZO NRs/CH3NH3PbI3/C with good properties was successfully fabricated,of which the superior performance may result from the high carrier mobility and conductivity of graphite.The study results suggested that the GZO NRs/CH3NH3Pbl3/C photodetector had a large Iph/Idark ratio of 1.8×103,a good responsivity of 0.32 A/W and a high detectivity of 1.3×1012 Jones at zero bias,respectively.Furthermore,the specified photodetector also possessed an excellent stability,and it may be due to that the graphite electrode with tens of microns thickness can served as a protective layer to isolate CH3NH3PbI3 from air,which optimizes the stability of perovskite effectively.