| Gallium oxide,a transparent semiconductor oxide material with ultra wide band gap(Eg-4.9 eV),has a good application prospect in the field of micro-level light electronics due to the Ga2O3 has the characteristics of high breakdown field strength,high temperature resistance,radiation resistance and good thermal stability,etc.It can be used to fabricate photodetector,UV filters,FET,photomultiplier,information storage,gas sensor,visible LED,UV LED,solar cells,fluorescent light-emitting devices,etc.It can be used for photocatalysis,such as purifying of water body,pollutant degradation.In addition,it has important application potential in transparent conductive electrode,optical window,ultraviolet communication and other aspects.With the rapid development of wearable electronics,the demand for large-area,light,portable and convenient sensors is also increasing.The integration of thin films on flexible substrates is an effective way to fabricate flexible electronic devices.Existing studies show that Ga2O3 thin films deposited directly on flexible substrates are amorphous.Ga2O3 film obtained by mechanical exfoliation method is difficult to control the thickness and area of the film.Besides,the film is fragile and easily damaged.In this paper,the influence of thin film thickness and external temperature on the photoelectric performance of MSM structure Ga2O3 photodetector is studied.On the basis of film preparation and device performance optimization,free-standing Ga2O3 film was prepared using the optimized parameters.The flexible Ga2O3 solar-blind photodetector and FTO/Ga2O3 heterojunction photodetector were further prepared by using free-standing Ga2O3 thin film.At the same time,we studied the photoelectric characteristics and band migration of transparent oxide heterojunction Sr3Al2O6/Ga2O3.The main research results are as follows:First,the effects of different deposition temperatures on the crystallization quality of Ga2O3 thin films were studied.Under the premise of optimizing the deposition temperature of the thin film,films of different thickness were prepared by controlling the deposition time of the thin film,and the effects of the film thickness on the crystallization quality and optical band gap of the Ga2O3 thin film were studied.The photoelectric performance of the MSM structure solar-blind photodetector based on Ga2O3 thin film was optimized from the film thickness.Due to the low thermal conductivity of Ga2O3,the performance of Ga2O3 based devices will degrade without a good heat dissipation mechanism.Here,the influence of external temperature(298K-623K)on the photoelectric performance of gallium oxide photodetector is studied.With the increase of temperature,the dark current increases monotonically,showing obvious semiconductor characteristics.The superlinear phenomenon that the photocurrent increases first and then decreases is mainly related to the self-trapped holes.The decrease of photosensitivity(the ratio of photocurrent to dark current)with the increase of temperature is mainly caused by the increase of dark conductance with the increase of temperature.Secondly,the layer Sr3A1206 films were prepared.In addition,the photoelectric characteristics and band alignment of Ga2O3/Sr3Al2O6 heterojunction were studied.Since gallium oxide is insoluble in water and highly transparent to visible light,Ga2O3 thin film can be used as a waterproof,high-temperature resistant material and optical window for Sr3Al2O6 thin film,considering the important application of Sr3Al2O6 in long afterglow luminescence.Third,free-standing Ga2O3 films were prepared.Using the above optimized film deposition parameters,the water-soluble sacrificial layer Sr3Al2O6 and Ga2O3 thin films were deposited on the substrate at high temperature(750?),and then the layer Sr3Al2O6 was dissolved by deionized water to obtain a large area of free-standing Ga2O3 thin film.the free-standing Ga2O3 film was transferred to different substrates to prepare the device.A flexible Ga2O3 diural-blind detector was fabricated by transfer Ga2O3 film to a flexible substrate PET.And its photoelectric performance under bending and non-bending conditions was studied.Finally,the free-standing Ga2O3 film was transferred to different substrates to prepare the device.The FTO is often used as a transparent electrode.The Ga2O3/FTO heterojunction photodetector with certain rectification characteristics is prepared by transferring the free-standing Ga2O3 thin film onto the FTO glass substrate.The valence band and conduction band at the contact interface between Ga2O3 and FTO are aligned by combining XPS and UV-Vis test. |
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