Preparation And Photoelectric Properties Of Bi₂Se₃ Thin Films

Since the two-dimensional materials represented by graphene were prepared,they have shown a very wide range of application scenarios in the semiconductor industry due to their superior performance over traditional materials in the low-dimensional scale.There are many kinds of two-dimensional materials,such as graphene and hexagonal boron nitride,as well as novel transition metal chalcogenides and topological insulators.For example,graphene,which has been studied a lot,has expanded its applications in optoelectronic devices,chemical sensors,high-performance batteries and in materials science.The two-dimensional material Bi₂Se₃is a kind of ideal strong topological insulator.It is a typical crystal with a energy gap of 0.3eV and a high thermoelectric coefficient.Compared with other two-dimensional materials,Bi₂Se₃ has a Fermi energy level located in the energy gap,and a Dirac surface state on its surface.Its various properties are very close to the ideal topological insulator material sought by people.Bi₂Se₃ has so many excellent optical and electrical properties that it has a great development space in semiconductor detectors and spin quantum devices.The thesis mainly covers the following aspects:1.The growth conditions of Bi₂Se₃ were systematically studied by controlling the growth temperature,growth region and carrier gas velocity in the experimental process by using the low cost,easy and controllable vapor deposition method.The experimental results were verified from two different orientations.Large areas of high quality Bi₂Se₃ thin films and single crystals were prepared on rigid Si O₂/Si substrates and flexible PI substrates respectively.The morphology of Bi₂Se₃ thin films and single crystals were analyzed and studied by various characterization methods.The controllable preparation of two-dimensional material Bi₂Se₃ was realized.2.By using Bi₂Se₃ thin films grown on different substrates as channel materials and using Ag as electrode,rigid and flexible two-dimensional thin film photodetectors based on Bi₂Se₃ materials were constructed respectively.We have tested and characterized the related performance of the detectors.Through the analysis of experimental data,it is confirmed that the photodetector based on Bi₂Se₃ thin films have both good optical response characteristics,and excellect wide spectral response capability in visible and infrared bands.It has the most important characteristics of flexibility,stability and fatigue resistance for flexible light detectors.In addition,the detectors have also been found to have the characteristics of self-powered optical detectors.It has great potential in future applications such as wearable devices.