【作者】 杨硕；

【导师】 张化宇；

【作者基本信息】 哈尔滨工业大学 ， 材料工程（专业学位）， 2020， 硕士

【摘要】 二维材料因其独特的层状结构导致量子限域效应等的发生,使其具备了优异的光学以及电学性能,从而引起了广泛关注。碲硒镓类化合物属于二维材料体系中重要的一类材料,包括GaTe、GaSe以及三元合金化合物。因其带隙宽度使其具备可见光光谱覆盖范围且光吸收系数高等优势,具有极大的潜力运用于光电探测器,催化,能源等各个领域。然而,可控制备出高质量与大面积的二维碲硒镓材料,仍是限制其进一步研究及应用的一大难题。因此二维碲硒镓化合物的可控制备,带隙调控等具有很高的研究价值。本文以二维GaTe、GaSe、GaSe_xTe_1-x为研究对象,采用了化学气相沉积法（CVD）制备了高质量的GaTe、GaSe薄膜与纳米带,以及三元GaSe_xTe_1-x纳米带并对其光电性质进行了探究。具体工作如下:（1）使用单质镓与Te粉为原料,采用化学气相法实现了二维GaTe的可控生长。分析了衬底、温度、保温时间、氢气比例对二维GaTe生长的影响。探究了二维GaTe形貌与相结构的关系,并发现可以通过生长温度的调控得到不同相结构比例的二维GaTe。在二维GaTe的生长中,这种以单质镓液为原料的CVD法凸显出了快速生长的优势,即使是10～60 s的保温时间就能生长出5～30μm的GaTe纳米片。同样,采用这种方法实现了二维GaSe薄膜的大面积生长,在温度750℃,气流量为100 sccm时,GaSe薄膜的横向尺寸超过了1000μm。通过此方法生长的GaSe薄膜厚度范围在1～6 nm之间,主要受加热温度的影响。通过光致发光光谱（PL）发现,随着厚度的减小带隙从1.95 e V减小至1.86 e V。（2）生长GaSe薄膜时,将温度升高至750℃,控制氢气比例减少至10 sccm,衬底上开始出现由三角形首尾相接相互交叠形成的GaSe纳米带。GaSe纳米带厚度约为4～6 nm,带隙约为1.96 e V,具有很高的结晶质量以及光致发光效率。基于GaSe纳米带制备了光电探测器器件,在5 V电压下,器件有1.9μA级别的光响应电流,开关比达到13。（3）选择Ga₂Se₃、GaTe、单质镓为生长原料,采用化学气相沉积法合成了三元GaSe_0.8Te_0.2纳米带。GaSe_0.8Te_0.2纳米带含Te百分比约为6.69,带隙为1.73e V,厚度约为20 nm。基于GaSe_0.8Te_0.2纳米带制备了光电探测器器件,器件在0℃下,5 V偏压的暗电流达到了20.38μA,光响应电流为0.869μA,具有良好的电导率与光电响应。并测试了其-125～0℃温度变化下器件性能的变化,随着温度的降低,GaSe_0.8Te_0.2纳米带的光响应电流降低,开关比逐渐增大,有着较好的光电子器件应用潜力。更多还原

【Abstract】 Due to its unique layered structure,the two-dimensional material has caused the occurrence of quantum confinement effects.It has excellent optical and electrical properties,which has attracted widespread attention.Because of it’s band gap width extending to visible light spectrum coverage and high light absorption coefficient advantages,it has great potential to be used in various fields such as photodetector s,catalysis,and energy.However,the controllable preparation of expected and large-area two-dimensional micron selenium materials is still a major problem that limits it’s further research and application.Therefore,the controllable preparation of two-dimensional selenium-selenium compounds and the reduction of band gap are very strong.Taking GaTe,GaSe,GaSe_xTe_1-x as the research object,using chemical vapor deposition（CVD）to prepare GaTe,GaSe thin films and nanobelts,And the ternary GaSe_xTe_1-x nanobelt and the photoelectric properties were investigated.The specific work is as follows:（1）Using elemental gallium and Te powder as raw materials,the controllable growth of two-dimensional GaTe is realized by chemical vapor method.The influence of substrate,temperature,heating time and hydrogen ratio on the growth of two-dimensional GaTe is analyzed.The relationship between two-dimensional GaTe morphology and phase structure was explored,and it was found that two-dimensional GaTe with different phase structure ratios can be obtained through the control of growth temperature.In the growth of two-dimensional GaTe,this CVD method using elemental gallium liquid as a raw material highlights the advantage of rapid growth.Even with a holding time of 10 to 60 s,GaTe nanosheets of 5 to 30μm can be grown.Similarly,this method is used to achieve large-area growth of two-dimensional GaSe thin films.At a temperature of 750℃and an air flow of 100 sccm,the lateral size of the GaSe thin film exceeds 1000μm.The thickness of the GaSe film grown by this method ranges from 1 to 6 nm,which is mainly affected by the heating temperature.According to photoluminescence spectroscopy（PL）,the band gap decreases from 1.95 e V to 1.86 e V as the thickness decreases.（2）When growing the GaSe thin film,increase the temperature to 750℃and reduce the proportion of hydrogen to 10 sccm.GaSe nanobelts formed by overlapping triangles end to end begin to appear on the substrate.The thickness of GaSe nanoribbons is about 4～6 nm,and the band gap is about 1.96 e V.It has high crystal quality and photoluminescence efficiency.A photodetector device is prepared based on GaSe nanoribbons.Under a voltage of 5 V,the device has a photoresponse current of 1.9μA,and the switch ratio reaches 13.03.（3）Choosing Ga₂Se₃,GaTe,and elemental gallium as growth materials,the ternary GaSe_0.8Te_0.2 nanobelt was synthesized by chemical vapor deposition.The GaSe_0.8Te_0.2 nanobelt has a Te percentage of 6.69,a band gap of 1.73 e V,and a thickness of about 20 nm.A photodetector device was prepared based on GaSe_0.8Te_0.2 nanoribbons.The dark current of the device under 0℃,5 V bias voltage reached 20.38μA,the photoresponse current was 0.869μA,and it has good electrical conductivity and photoelectric response.And tested the change of the device performance under the temperature change of-125～0℃.As the temperature decreases,the photoresponse current of the GaSe_0.8Te_0.2 nanobelt decreases,and the switching ratio gradually increases,which has a good application potential for optoelectronic devices.更多还原