Preparation Of High K-gate/ Perovskite Transistors And Study On Their Photoelectric Dual Regulation Characteristics

Recently,researchers at home and abroad have carried out a certain amount of research on the phototransistor based on perovskite material,however,there are still many problems which directly restrict the improvement of device performance.In this work,we used FAPbI₃ as active layer,HfO₂ high k material instead of common SiO₂ as dielectric layer to prepare high performance phototransistor,and studied the effect of self induced passivation of perovskite on the performance of the device.This word provides theoretical support for the development of high performance photoelectric transistor.The HfO₂ high dielectric films were prepared by the atomic layer deposition method,and the effects of the substrate pretreatment,deposition temperature and deposition cycle on the dielectric properties of the films were studied.The morphology,phase composition and dielectric properties of the films were analyzed by means of AFM,XRD,XPS,TEM,dielectric property test and other characterization methods.The experimental results show that the HfO₂ films prepared by using ALD method are mainly in amorphous form.The substrate pretreatment process has great influence on the uniformity of the film,and the substrate with Plasma treatment has good uniformity and very low surface roughness.The temperature mainly affects the leakage current and dielectric constant of the film,and the electrical properties of the films deposited under 200? are the best.There is a good linear relationship between the deposition cycle number and the film thickness,and the film leakage current and dielectric constant of cycle cyclic deposition have reached excellent level.The effects of the solvent,annealing temperature and the first step speed of the two-step process on the morphology,phase composition and photoelectric properties of a acetamiprid lead-calcium iodide-perovskite thin film were studied by two-step spin-coating method.By means of SEM,XRD,PL,UV-Vis,I-V characteristic test,the experimental results show that by using the DMF-DMSO mixed solvent the PbI₂ residue in the planar structure device can be reduced effectively,and the crystallization of the film can be better,more excellent photoelectric performance can be obtained as well.In the two-step process,the annealing temperature and the first rotational speed of the film will affect the crystallization of the film,while the film with good crystallinity can perform better.The thickness of the film can be controlled effectively by adjusting the speed of the first step of the two steps.The thin film transistor was prepared by spinning the perovskite film on the ALD deposited HfO₂ dielectric film and then evaporating the electrode.In this experiment,the influence of the self induced passivation on the interface and macroscopic properties of the device is studied,and the device is characterized by SEM,XRD,PL,UV-Vis,PL,TRPL,neutron reflection and so on,the experimental results show that the residual PbI₂of perovskite can effectively increase carrier lifetime and then affect device performance by passivate the interface.The devices prepared by this method exhibit the characteristics of a bipolar transistor with a light response of 400 A W^-1.