【作者】 李芳；

【导师】 王泽高； 郝昕；

【作者基本信息】 四川大学 ， 材料工程（专业学位）， 2022， 硕士

【摘要】 红外探测作为一种应用广泛的技术,在信息通信、军事、遥感、生物医学成像等领域起着至关重要的作用,而光电探测材料是制约红外探测器性能的核心和关键。传统光电探测材料具有工作环境严苛、薄膜制备成本高昂、探测波段范围有限等各种局限性,已无法满足当前科学技术发展所需的高性能、宽波段、快速的光电响应。二维过渡金属硫族化合物因其原子级厚度、高载流子迁移率和极易调整的电子结构,表现出丰富的物理特性。其中Pt基硫族化合物相较Mo/W基具有更丰富的d电子数量、更窄的带隙、更高的空气稳定性以及更丰富的载流子类型,有望实现高性能、宽光带广谱红外探测。然而当前针对Pt基硫族化合物的研究还处于初期阶段,高质量、大面积、均匀的Pt基硫族化合物薄膜的生长与调控亟待解决。本文采用直接硫/硒化法以及化学气相沉积法对PtS和PtSe2薄膜的制备进行了系统的研究,通过光电测试平台研究了PtS和PtSe2的基础电学特性以及光电探测性能,构筑了Mo S2/PtS异质结并对其红外探测性能进行了测试,系统地讨论了外场、光波长和光功率对探测器响应度、比探测率以及响应时间的影响。本文首先采用直接硫化法对PtS薄膜的生长进行了系统的探索并最终获得了一种具有p型导电特性的新型二维薄膜材料。通过对预先沉积的金属Pt厚度以及生长温度等参数进行探索,最终确认了PtS薄膜的最佳生长条件并通过不同表征手段得到了PtS的晶体结构、原子比例等信息,得到的PtS为四方相晶体结构,晶面间距为0.368 nm,Pt:S的原子比值约为0.97。研究表明PtS薄膜的厚度取决于预先沉积的金属Pt厚度,沉积的Pt厚度与得到的PtS薄膜厚度比例约为1:10。PtS薄膜均匀性和连续性随温度的升高呈现出先增加后下降的趋势,载流子迁移率随薄膜厚度增加先增大后减小,其中1 nm的Pt厚度在650℃下得到的样品载流子迁移率约为0.02 cm2·V-1·s-1。光电性能测试显示PtS具有p型导电特性以及负光电响应,响应度和比探测率分别为1.65 A·W-1、1.6×1010 Jones。不同方法制备PtSe2的探索实验中,直接硒化法和原子扩散法分别可以得到晶粒尺寸约为40 nm的多晶薄膜以及粗糙度极大的PtSe2,综合考虑晶粒尺寸、薄膜均匀性遴选出Na Cl辅助的化学气相沉积法作为实现单晶PtSe2可控生长的手段,通过对前驱体源、温度、压强等关键生长参数进行调控得到了横向尺寸可达30μm的六边形或三角形单晶PtSe2。基础电学测试结果显示PtSe2表现出典型的金属电学性质:电导率最大可以达到1.37×104 S·m-1,优于常见的Mo S2等半导体薄膜材料。不同厚度PtSe2均表现出电阻随磁场强度连续变化的磁阻效应,磁阻变化率(MR)最大范围为-1.8%~3.7%,磁场的双向扫描过程中出现明显的磁滞回线,表明本文制备得到的PtSe2具有铁磁性。基于PtSe2良好的导电性将其作为电极材料,探索PtSe2电极上PtS的光电响应性能,结果显示PtSe2电极上PtS仍表现出负光电响应以及与Ti电极上PtS的响应性能相当,响应度和比探测率分别为1.46 A·W-1、2.57×1010 Jones。研究表明p-n结的内建电场能促进光生电子与空穴的有效分离,有望进一步实现高性能、宽波段红外光电探测,因此为了进一步探究Pt基硫族化合物在红外光电探测领域的应用前景同时考虑到PtS的光电响应性能有待提升,基于本文制备得到的p型PtS薄膜和现有的n型Mo S2搭建了Mo S2/PtS异质结。开尔文力显微镜对异质结表面接触电势的测试结果显示接触电势差为160 m V;将异质结作为沟道材料构建了异质结基光电探测晶体管,探究了背栅电压对不同光波长及功率下响应性能的影响。响应度、比探测率、响应时间等性能参数的系统性测试和分析结果表明,外场可以通过photogating效应调节光与物质的相互作用,从而对材料的光响应性能进行调控,最终实现了从可见光到近红外的高性能、宽波段光电探测。Mo S2/PtS异质结在400 nm波长下的响应度和比探测率最大值分别可以达到25.43 A·W-1和8.54×1012 Jones,在红外波段(900 nm)仍具有一定的探测性能,响应度和比探测率分别为0.88 A·W-1、9.90×1010 Jones。更多还原

【Abstract】 Infrared detection,as a widely used technology,plays a vital role in information communication,military,remote sensing,biomedical imaging and other fields,and photoelectric detection materials are the key to restrict the performance of infrared detectors.The limitations of traditional photoelectric detection materials such as strict working environment,high-cost film preparation technology and limited detection performance can not meet the high performance,wide band and fast photoelectric response required by current scientific and technological development.Two-dimensional transition metal chalcogenide because of its atomic thickness,high carrier mobility and easy to adjust the structure of electronic,show the rich physical properties,where the Ptbased chalcogenides has more abundant d electronic quantity,a narrower band gap,higher air stability and more abundant carrier type than Mo/W based chalcogenides are expected to achieve high performance,wide band spectrum,infrared detection.However,the current research on Pt-based chalcogenides is still in the early stage,the growth and regulation of high-quality,large-area and uniform Pt-based chalcogenides films need to be solved urgently.In this paper,the direct sulfuration/selenization method and chemical vapor deposition method were used to systematically study the preparation of PtS and PtSe2 thin films.The basic electrical properties and photoelectric detection performance of PtS and PtSe2 were studied through the photoelectric test platform,and the Mo S2/PtS heterojunction was constructed and its infrared detection performance was tested.The effects of field,wavelength and power on responsivity,specific detection rate and response time are systematically discussed.In this paper,the growth of PtS thin film was systematically investigated by direct sulfuration method and a new type of two-dimensional thin film with p-type conductivity was obtained.By studying the pre-deposited metal Ptthickness and growth temperature and other parameters,the optimal growth conditions of PtS film were finally confirmed,and the crystal structure and atomic ratio of PtS film were obtained by different characterization methods.The obtained PtS was tetragonal crystal structure,the interplanar crystal spacing was 0.368 nm and the atomic ratio of Pt:S was about 0.97.The study shows that the thickness of PtS film depends on the pre-deposited Ptthickness,and the ratio of deposited Ptthickness to the obtained PtS film thickness is about 1:10.The uniformity and continuity of PtS films increased first and then decreased with the increase of temperature,and the carrier mobility increased first and then decreased with the increase of film thickness.The carrier mobility of samples with 1 nm Ptthickness at 650 ℃ was about 0.02 cm2·V-1·s-1.Photoelectric performance test showed that PtS had p-type conductivity and negative photoelectric response,with responsivity and specific detectivity of 1.65A·W-1 and 1.6×1010 Jones,respectively.In the exploration experiments of preparing PtSe2 by different methods,polycrystalline PtSe2 films with grain size of about 40 nm and with great roughness can be obtained by direct selenization method and atomic diffusion method respectively.Nacl-assisted chemical vapor deposition is selected as the means to realize the controllable growth of single crystal PtSe2 by taking the grain size and film uniformity into consideration.Hexagonal or triangular single crystal PtSe2 with lateral size up to 30 μm was obtained by adjusting key growth parameters such as precursor source,temperature and pressure.Basic electrical test results show that PtSe2 exhibits typical metal electrical properties: The maximum conductivity can reach 1.37×104 S·m-1,which is better than the common semiconductor film materials such as Mo S2.Moreover,PtSe2 with different thickness shows the magnetic resistance effect of continuous change with magnetic field intensity,and the maximum range of magnetic resistance change rate(MR)is-1.8%~3.7%.Obvious hysteresis loops appear in the bidirectional magnetic field scanning process,indicating that the prepared PtSe2 has ferromagnetism.Based on the good conductivity of PtSe2,the effect of PtSe2 as electrode material on the photoelectric response performance of PtS was investigated.The results showed that PtS still showed negative photoelectric response and the response performance was comparable to that of PtS on Ti electrode,with the responsivity and specific detectivity of 1.46 A·W-1 and 2.57×1010 Jones,respectively.The research shows that the built-in electric field of p-n junction can promote the effective separation of photogenerated electrons and holes,which is expected to further realize high-performance,wide-band infrared photoelectric detection.Therefore,in order to further explore the application prospect of Pt-based chalcogenides in the field of infrared photoelectric detection and take into account the photoelectric response performance of PtS to be improved,The Mo S2/PtS heterojunction was constructed based on the p-type PtS film prepared in this paper and the existing n-type Mo S2.The results of kelvin force microscope show that the contact potential difference is 160 m V.The heterojunction was used as channel material to construct a heterojunction-based photoelectric detection transistor.The effect of backgate voltage on the response performance of different light wavelengths and powers was investigated.Systematic testing and analysis of responsivity,specific detectivity,response time and other performance parameters indicate that photogating can modulate the light-substance interaction to regulate the photoresponse performance of materials,and ultimately achieve high-performance,wide-band photoelectric detection from visible light to near-infrared.The maximum responsivity and specific detectivity of Mo S2/PtS heterojunction at 400 nm can reach25.43 A·W-1 and 8.54×1012 Jones,respectively,which still has certain detection performance in infrared band(900 nm).The responsivity and specific detectivity were 0.88 A·W-1 and 9.9×1010 Jones,respectively.更多还原