SnO2纳米棒阵列/AlN/p-GaN异质结的制备及其紫外发光特性研究

Due to the wide band gap and high exciton binding energy, SnO2 is considered to be a promising material for the realization of ultraviolet (UV) light-emitting diode. However, the dipole-forbidden rule and the unfavorable band offsets prohibit the band-edge radiative transition and UV emission of SnO2 heterojunction UV light-emitting diode. In this project, the nanocrystalline SnO2 nanorod arrays are synthesized by using ZnO nanorod arrays as template, and the crystallite size and the surface morphology of the SnO2 nanorod are modulated to realize the UV emission of SnO2 via breaking the dipole-forbidden rule. The effects of crystallite size and surface morphology on the UV band-edge emission are investigated, and the synergistic effect from crystallite size and surface morphology is further explored. The nanocrystalline SnO2 nanorod arrays/AlN/p-GaN heterojunction UV light-emitting diode is fabricated by using AlN barrier layer as an electron blocking layer. The impacts of the crystalline quality and thickness of the AlN barrier layer on the carrier transportation and UV emission of the heterojunction are explored. The coordination optimization of the crystalline quality and thickness of the AlN barrier layer is built up to improve the emission efficiency. The solvement of above issues has scientific significance for the study of UV emission mechanism of SnO2, and also has important application value for the development of SnO2-based UV light-emitting device.

SnO2具有禁带宽度大、激子束缚能高的优点，在制造紫外发光二极管方面具有潜在的应用价值。然而“偶极禁阻”规则的束缚和不合适的能带偏移严重制约了SnO2异质结紫外发光二极管的光电性能。本项目拟以ZnO纳米棒阵列为模板制备纳米晶SnO2纳米棒阵列，通过对SnO2纳米棒的晶粒尺寸和表面形貌进行调控，研究晶粒尺寸和表面形貌对SnO2的紫外光发射性能的影响，探索晶粒尺寸和表面形貌的协同作用，从而打破“偶极禁阻”规则，实现紫外光发射；进一步引入AlN势垒层作为电子阻挡层构筑纳米晶SnO2纳米棒阵列/AlN/p-GaN异质结紫外发光二极管，研究AlN势垒层的晶体质量和厚度对异质结的载流子输运和紫外发光性能的影响，建立AlN势垒层的晶体质量和厚度的优化协同，提高异质结的紫外发光效率。上述问题的解决对于研究SnO2的紫外光发射机理具有重要的科学意义，对推动高效SnO2基紫外发光器件的发展具有重要的应用价值。

打破偶极禁阻规则的制约实现SnO2的紫外电致发光，并且降低载流子的非辐射复合，对于SnO2异质结紫外发光二极管来说是非常重要的。本项目以ZnO纳米棒阵列为模板制备了ZnO@SnO2核壳纳米棒阵列和SnO2空心纳米棒阵列，研究了液相沉积反应参数和退火温度对样品的表面形貌和晶体结构的影响；通过调控SnO2壳层的晶粒尺寸，实现了SnO2的紫外光致发光。制备了ZnO@SnO2核壳纳米棒阵列紫外探测器，对比研究了SnO2壳层对探测器紫外光响应性能的影响，结果表明SnO2壳层能有效提高探测器的响应度，并降低响应时间。进一步制备了ZnO@SnO2核壳纳米棒阵列/p-GaN异质结发光二极管，研究了ZnGa2O4界面层和SnO2壳层对载流子输运和电致发光的影响，结果表明ZnGa2O4界面层能有效的阻挡ZnO@SnO2核壳纳米棒中的电子注入p-GaN，而SnO2壳层中局域态可以束缚部分来自p-GaN的隧穿空穴与电子发生辐射复合，进而导致ZnO@SnO2核壳纳米棒的紫外光发射。此外，还制备了CuO/ZnO自供电紫外探测器和ZnO/Zn2TiO4核壳纳米棒阵列，并对其紫外光探测性能和可见光催化性能进行了研究。本项目研究为探索氧化物半导体光电器件的应用提供了理论和实验支持。