Self-powered Solar-blind Photodetector Based On Ti₃C₂T_x/Ga₂O₃

Solar-blind ultraviolet photoelectric detectors have great potential applications in military and civil fields such as national defense early warning,tail flame guidance,space exploration,security communication,fire alarm,environmental monitoring,ultraviolet radiation detection,and defogging navigation,and have received extensive attention in recent years.Gallium oxide（Ga₂O₃）,a new ultra-wide bandgap semiconductor material with a bandgap width of 4.2-5.1 e V,has a photoresponse in the entire solar blind deep ultraviolet region（200-280 nm）,and has the advantages of high atomic shift threshold energy,strong radiation resistance,and good chemical and physical stability.It is an optimal material for the preparation of solar blind ultraviolet photodetectors.Due to the shortage of traditional energy,detectors are increasingly tending to be energy-saving,efficient and miniaturized.Self-powered detectors can work by themselves without external voltage,so detectors with self-powered performance begin to emerge.Ti₃C₂T_x is a newly discovered graphene-like two-dimensional material with extremely high carrier mobility and excellent light transmission from deep ultraviolet to infrared spectral band.It is a transparent conductive electrode with excellent compatibility with photodetectors.Based on the high solar blind light detection efficiency of Ga₂O₃ and the high carrier transmission capacity of Ti₃C₂T_x,Schottky,phase junction and photochemical self-powered solar blind detectors are constructed to optimize and improve the solar blind photoelectric performance of the detectors.The physical mechanism of the detectors is analyzed in depth.The main results are as follows:1.Ti₃C₂T_x/β-Ga₂O₃ thin film Schottky self-powered solar blind detector.In view of the intrinsic defects of gallium oxide materials,which inevitably produce oxygen vacancies,plasma treatment is used to reduce the oxygen vacancies on the surface ofβ-Ga₂O₃ film to strengthen the Schottky potential barrier between Ti₃C₂T_x film andβ-Ga₂O₃film.The work function of Ti₃C₂T_x is large,and it is suitable to construct a Schottky solar blind detector withβ-Ga₂O₃.Without plasma treatment,the light-dark ratio of the detector is 4.6×10³,the photoresponsiveness is 0.04 m A/W,and the response speed is 0.53 s/1.26s under the test condition of 254 nm UV light with 0 V bias and light intensity of 1000μW/cm2.The proportion of oxygen vacancies inβ-Ga₂O₃ films decreased from 44.5%to27.3%after treatment ofβ-Ga₂O₃ films with oxygen plasma.Under the same conditions,the light-dark ratio of the Ti₃C₂T_x/β-Ga₂O₃ film Schottky self-powered solar-blind detector is 2.7×104,which is 490%higher than that of the untreated one,and the photoresponsiveness is 0.26 m A/W,which is 550%higher than that of the untreated one.The light response speed was 83 ms/44 ms and 447 ms/1216 ms were accelerated.2.Ti₃C₂T_x/β-Ga₂O₃ nanocrystalline Schottky self-powered solar-blind photodetector.In view of the small specific surface area of Ga₂O₃ film and the existence of light reflection,which reduces the performance of the device,the vertical nanopilar structure is introduced to increase the effective light absorption area ofβ-Ga₂O₃.Theβ-Ga₂O₃nanocolumn array was prepared by hydrothermal growth of Ga OOH precursor,and the nanocolumn Schottky self-powered solar blind detector was constructed by using Ti₃C₂T_xas the electrode.Ti₃C₂T_x was dispersed on the surface ofβ-Ga₂O₃ nanopularization,and Ag nanowires were used to connect the dispersed Ti₃C₂T_x into electrodes.The Ti₃C₂T_x/β-Ga₂O₃ self-powered solar blind detectors and Ag NWS-Ti₃C₂T_x/β-Ga2O3 self-powered solar blind detectors were constructed respectively.Compared with the Ti₃C₂T_x/β-Ga₂O₃ thin film Schottky solar blind detector,the photocurrent of Ti₃C₂T_x/β-Ga₂O₃self-powered solar blind detector reaches 200 n A under 254 nm UV light test conditions of 0 V bias and 1000μW/cm2,the photocurrent of Ti₃C₂T_x/β-Ga₂O₃ self-powered solar blind detector is increased by 199%.The light responsivity is 0.36 m A/W,which is increased by 38%.The performance of the Ag nanowire detector is further improved.Under the same test conditions,the photocurrent of the Ag NWs-Ti₃C₂T_x/β-Ga₂O₃vertical structure solar blind detector is 800%higher than that of the Ti₃C₂T_x/β-Ga₂O₃nanowire Shottky solar-blind detector at 1800n A.The light responsivity is improved by 870%to 3.5 m A/W.3.Ti₃C₂T_x/α/β-Ga₂O₃ nanocolumn Phase Junction self-powered solar blind detector.On the basis of the previous chapter,different phases of Ga₂O₃ nanopelms were prepared,and the phase junction structure was introduced to enhance the built-in electric field strength.The precursor of Ga OOH grown by hydrothermal method was prepared intoα-Ga₂O₃ after annealing.On the basis ofα-Ga₂O₃,α/β-Ga₂O₃ was prepared by rapid annealing.Ag NWs-Ti3C2Tx/α-Ga2o3 nanocrystal self-powered solar blind detector and Ag NWs-Ti₃C₂T_x/α/β-Ga₂O₃ nanocrystal phase-junction self-powered solar blind detector were constructed.The formation of the second type energy band at the phase junction interface can promote the rapid separation of photogenerated carriers.The photocurrent of the Ag NWs-Ti₃C₂T_x/α/β-Ga₂O₃ nanocolumn junction self-powered solar blind detector reaches 2.9μA,which is 1.1μA higher than that ofβ-Ga₂O₃ detector and2.88μA higher than that ofα-Ga2o3 detector.The responsiveness is up to 5.2 m A/W.4.Ti₃C₂T_x/α-Ga₂O₃ nanocrystalline photoelectrochemical self-powered solar blind detector.To fill the shortage ofα-Ga₂O₃ nanopilar detector in the previous chapter,a photochemical type photodetector is introduced.Photochemical（PEC）photodetectors are new self-powered photodetectors.Due to the special dynamic mechanism formed by solid-liquid contact between electrons and holes,directional electron movement will occur and electric current will be generated.The photochemical self-powered solar blind Ti₃C₂T_x/α-Ga₂O₃ nanocolumn detector was fabricated by drip-coating Ti₃C₂T_x onα-Ga₂O₃ nanocolumn.The photoresponsiveness of the detector to 254 nm light is 2.75m A/W at 0 V.