SnSe薄膜制备及其光电性质研究

发布时间：2018-03-01 15:11

本文关键词： 铁电极化铌酸锂 Sn Se薄膜光电调控脉冲激光沉积　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：Sn Se作为一种p型的窄禁带半导体材料,其体材料的直接带隙为1.3 e V,可吸收大部分波段的太阳光。作为IV-VI族化合物的一员,除了具有本族化合物常见的优异性质外还具有其它特殊的性质:层状结构,具有各向异性,优异的光电和热电性质等。针对元器件的低维化,集成化的需求,材料的薄膜化已成为重要发展趋势。在薄膜化的基础上,将铁电材料与半导体薄膜结合,利用铁电材料的极化性质对半导体的能带结构和传输性质进行调控,实现无源的介电器件和有源的半导体器件的结合也成为重要的研究热点之一。本文探索了利用PLD和旋涂技术进行Sn Se薄膜的制备,得到不同极化方向的光铁电铌酸锂/光电半导体Sn Se薄膜异质结,利用铁电材料不同方向的极化电场与外加光场耦合来调控薄膜的光电性质,得到一种双色光电探测器件。本文制得了结晶质量较好的纯相Sn Se薄膜,PLD生长薄膜的速度为2nm/min。光场和极化电场耦合作用对Sn Se薄膜的光电性质起到了较好的调控效果。首先在暗场条件下,不同极化方向的电导产生四倍值的差距。在极化场作用下,极化方向指向薄膜的样品引入屏蔽电子,薄膜处于高阻态;极化方向背向薄膜的样品,薄膜中引入屏蔽空穴,处于低阻态。这一结论在旋涂薄膜中也得以验证。特别地,在405 nm激光照射下,对于极化方向指向薄膜的样品,极化场会使铌酸锂与Sn Se接触处的界面电势下降,由于接触后铌酸锂的导带位置低于Sn Se导带位置,当铌酸锂发生光电子跃迁,光电子并不能向Sn Se导带进行传输,而空穴可以在铌酸锂价带位置向薄膜传输,会增加薄膜光电导;对于极化方向背向薄膜的样品,会使界面两侧电势能增加,铌酸锂能带向上弯曲超过Sn Se能带,而在发生光电效应时,光电子可以向薄膜进行传输,降低p型薄膜的光电导。通过利用光、电场耦合调控n型Cd Se半导体薄膜的结果,第五章进一步验证了调控模型。Cd Se在405 nm波长激光作用下出现了相反的调控现象,当极化方向指向薄膜,Cd Se的光电导相比632 nm照射下出现降低的现象,正是由于极化场使界面两侧的势能降低,会有空穴向薄膜传输,而在另一极化方向的样品中,极化场使界面两侧的电势增加,铌酸锂的导带高过Sn Se的能带,会有光电子向薄膜传输,光电导并没有降低反而会出现增加。
[Abstract]:As a p-type narrow band gap semiconductor material, Sn se has a direct band gap of 1. 3 EV and absorbs most of the solar light. It is a member of IV-VI family compounds. In addition to the common excellent properties of their own compounds, they also have other special properties: layered structure, anisotropy, excellent optoelectronic and thermoelectric properties, etc. The thinning of materials has become an important development trend. On the basis of thinning, ferroelectric materials are combined with semiconductor thin films to regulate the energy band structure and transport properties of semiconductors by using the polarization properties of ferroelectric materials. The combination of passive dielectric devices and active semiconductor devices has also become one of the important research hotspots. In this paper, the preparation of Sn se thin films by PLD and spin coating techniques has been explored. The photoferroelectric lithium niobate / photodiode Sn se thin films with different polarization directions are obtained. The optoelectronic properties of the films are controlled by the coupling of the polarized electric field in different directions of ferroelectric materials with the external light field. A two-color photodetector is obtained. In this paper, the growth rate of pure phase Sn se thin film grown by PLD is 2 nm / min. The coupling of optical field and polarization electric field has a good effect on the photoelectric properties of Sn se thin film. Effect. First of all in the dark field conditions, Under the action of polarization field, the polarization direction leads to the introduction of shielded electrons into the film, and the film is in a high resistance state. This conclusion is also verified in spin-coated films. In particular, the interfacial potential of lithium niobate contact with Sn se decreases when the polarization direction is directed to the film under 405 nm laser irradiation. Because the conduction band position of lithium niobate is lower than that of Sn se after contact, when photoelectron transition occurs in lithium niobate, the photoelectron can not be transported to Sn se conduction band, but the hole can transport to the thin film at the valence band position of lithium niobate. The photoconductivity of the film is increased, and the potential energy on both sides of the interface increases for the sample with the polarization direction backward, and the band of lithium niobate bends upwards over the Sn se band, and in the event of photoelectric effect, the photoelectron can be transported to the film. The photoconductivity of p-type thin films is reduced. By using light and electric field coupling to control n-type CD se semiconductor films, chapter 5th further verifies that the regulation model, CD se, has the opposite regulation phenomenon under the action of 405nm wavelength laser. When the polarization direction is directed to the film, the photoconductivity of CD se decreases compared with that of 632 nm irradiation. It is precisely because the polarization field makes the potential energy on both sides of the interface lower, there will be hole transmission to the film, while in the other polarization direction sample, The polarization field increases the electric potential at both sides of the interface, and the conduction band of lithium niobate is higher than that of Sn se, and there will be photoelectron transmission to the thin film. Instead of decreasing the photoconductivity, the photoconductivity will increase.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ134.32;TB383.2

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