钛酸锌和锡酸锌单晶薄膜的异质外延生长及性质研究

Zinc titanate and zinc stannate are inorganic functional materials with excellent photoelectric properties, they can combine the advantages of zinc oxide and titanium (tin) oxide. Therefore, they are very promising wide band gap semiconductor materials. But at present, there are no zinc titanate and zinc stannate bulk single crystal materials. By using metal organic chemical vapor deposition (MOCVD) method, zinc titanate and zinc stannate single crystal films will be heteroepitaxially grown on a variety of single crystal substrates. Lattice matching and process conditions for the zinc titanate and zinc stannate films grown on different substrates will be investigated systemically. The single crystal substrates including the crystal surface orientation suitable for epitaxial growth of the films will be selected and the optimum processing parameter of the film growth will be determined. Single crystal zinc titanate and zinc stannate epitaxial films with high electron mobility and low defect density will be obtained; Lattice microstructure, defect morphology, electrical and optical properties of the films will be studied. The growth mechanism, epitaxial relationship, electron transport mechanism and photoluminescence mechanism of the films will be clarified; Effective doping elements will be screened and determined. The existence form of doped atoms and the influence of doping concentration on the structure and photoelectrical properties of the films will also be studied. The corresponding doping and conducting mechanism will be clarified; The preparation of zinc titanate and zinc stannate based Field-Effect TFT will be explored tentatively together with the device performance. High quality zinc titanate and zinc stannate epitaxial single crystal films have potential application prospects in the field of transparence electron devices and optoelectric devices. The forward looking research work will lay the necessary foundation for its application in the aspect of semiconductor devices.

钛酸锌和锡酸锌是光电性能优异的无机功能材料，可兼备氧化锌和氧化钛（锡）的优点，因此是很有潜力的宽带隙半导体材料，但目前尚无钛酸锌和锡酸锌体单晶材料。拟用多种单晶片为衬底，用MOCVD方法异质外延生长钛酸锌和锡酸锌单晶薄膜。系统地研究不同衬底上生长钛酸锌和锡酸锌薄膜的晶格匹配和工艺条件，筛选出适合的单晶衬底及晶面取向，确定最佳的工艺参数，制备出高电子迁移率、低缺陷密度的钛酸锌和锡酸锌单晶薄膜；研究薄膜的晶格微结构、缺陷形态和光电性质，弄清薄膜的生长机制、外延关系、电子输运机制和光致发光机制；筛选确定有效掺杂元素，研究掺杂原子的存在形态及掺杂浓度对薄膜结构和光电性能的影响，弄清掺杂机理和导电机制；尝试制备钛酸锌和锡酸锌基场效应薄膜晶体管,研究其性能。高质量的钛酸锌和锡酸锌外延单晶薄膜在透明电子器件和光电器件领域具有潜在的应用前景，该前瞻性的研究工作将为其在半导体器件方面的应用奠定必要的基础。

钛酸锌和锡酸锌的光电性能优异，可兼备氧化锌和氧化钛（锡）的优点，其带隙大于氮化镓和碳化硅材料，因此是很有潜力的宽带隙半导体材料。由于尚无钛酸锌和锡酸锌体单晶材料，限制了其在半导体光电器件领域的应用。因此外延生长出高质量的钛酸锌和锡酸锌单晶薄膜，实现薄膜电学性质的调控是非常必要的。我们研究了制备薄膜工艺条件和薄膜-衬底的晶格匹配情况，找到与所需制备不同晶型薄膜相匹配的单晶衬底材料；选用MgAl2O4、MgO、LiNbO3、LiTaO3等多种单晶片作为衬底，采用MOCVD和PLD方法，在优化制备工艺条件的基础上，成功制备出正钛酸锌（Zn2TiO4）、偏钛酸锌（ZnTiO3）、正锡酸锌（Zn2SnO4）和偏锡酸锌（ZnSnO3）外延薄膜，系统研究了制备薄膜的晶格结构、形貌、外延机制、组分和光学性质等，明确其外延关系；制备出不同钽掺杂浓度的Zn2SnO4和Zn2TiO4外延薄膜，研究了薄膜的结构、光电性质和掺杂机理。3%Ta掺杂Zn2SnO4薄膜的霍尔迁移率约为19.8 cm^2/V·s，薄膜电阻率约为1.03×10^3 Ω·cm；2%Ta掺杂Zn2TiO4薄膜的载流子迁移率约为28.2 cm^2/V·s，载流子浓度为1.22×10^16 cm^-3。基于钽掺杂Zn2SnO4薄膜制备出紫外光电探测器。在254 nm光照下，基于3%Ta掺杂Zn2SnO4薄膜制备探测器的光响应度约为23.3 A/W，5V偏压下其光暗电流比大于10^4。此外，基于钽掺杂氧化钛薄膜制备出薄膜晶体管（TFT），研究了器件的性能。高质量的钛酸锌和锡酸锌外延单晶薄膜在透明电子器件和紫外探测器等领域有着广阔的应用前景，对钛酸锌和锡酸锌单晶外延薄膜材料的制备及其电学性能调控进行系统地研究，将为该材料在电子器件方面的实际应用奠定良好的基础。