【作者】 张艳杰；

【导师】 王金斌；

【作者基本信息】 湘潭大学 ， 微电子学与固体电子学， 2009， 硕士

【摘要】 ZnO是一种宽禁带的新型II-VI化合物半导体材料,具有六角钎锌矿结构,同时它是一种独特的材料,具备光电、压电等性能。特别地,由于其禁带宽度大(3.37 eV),激子结合能高(60 meV),室温下具有高效的激子受激发光,所以,ZnO在短波长光电器件领域有着极大的应用潜力,如发光二极管(LEDs)和激光器(LDs)等。要实现ZnO在光电领域的广泛应用,首先必须获得性能良好的n型和p型ZnO材料。但是由于缺陷的影响,ZnO的发光效率较低。尽管控制缺陷对于提高ZnO发光效率具有重要意义,但是缺陷相关的电子-空穴复合机制尚未明确。本文利用雾化气相沉积法制备了ZnO晶体薄膜,分析不同衬底温度及退火气氛对ZnO表面形貌及发光性能的影响,发现2.39 eV处绿光发光峰的起源与氧空位有着密切的关系。利用脉冲调制等离子体炉氢化处理ZnO薄膜,改变氢化时样品与等离子之间的距离,分析氢化处理对发光性能的影响。室温CL光谱表明,氢化处理能够提高紫外发光效率(3.27 eV),并且发光效率提高的幅度与氢化条件关系密切。当距离从90 mm减小至75 mm时,紫外发光及绿光发光强度均先增加后降低。低温下的CL测试发现,对ZnO样品氢化处理后,3.315 eV发光峰成为优势的发光带。研究表明,氢与本征缺陷能够形成浅施主络合物,提高了浅施主的浓度,对于提高紫外光发光效率有重要意义。论文第五章利用溶胶-凝胶法制备了Li掺杂ZnO多晶薄膜。样品保持了钎锌矿结构。室温CL测试表明,随Li掺杂浓度的增加,无辐射复合中心浓度增加,样品的发光效率降低。通过分析样品低温下的CL光谱,3.28及3.31 eV两处的发光峰归因于LiZn及LiZn-Lii受主束缚激子跃迁。Zn1-xLixO薄膜(0.08≤x≤0.12)具有室温铁电电滞回线,锂锌替代及锂相关络合物是导致Li掺杂ZnO薄膜具有铁电性的原因。更多还原

【Abstract】 Zinc oxide (ZnO) is a novel II-VI compound semiconductor with a hexagonal wurtzite structure. ZnO is a unique material that exhibits optoelectronic, piezoelectric, and ferromagnetic multiple properties. In particular, it is a potential candidate for applications in short-wavelength optoelectronic devices, including light emitting diodes (LEDs) and laser diodes (LDs), due to its direct wide-bandgap (3.37 eV) and high exciton binding energy (60 meV), which will favor efficient excitonic emission processes at room temperature. To prepare applied optoelectronic devices, high quality n-type and p-type ZnO must be synthesized. However, because of the charge compensation of native defects such as vacancies and interstitials, the UV emission efficiency of ZnO is low. Moreover, the mechanism behind the defect related electron–hole recombination process in ZnO is still unclear, although the control of defect states is the most important issue for the improvement of emission efficiency. In this paper, pure ZnO thin films have been prepared by a spray chemical vapor deposition method. The effect of substrate temperature and anneal conditions on surface morphology and luminescent properties of ZnO thin films was studied. The origin of 2.39 eV transition is related to oxyqen vacancy.A pulse-modulated plasma high-power inductively coupled plasma (PM-ICP) was applied to the hydrogenation of ZnO thin films. Distances between ZnO and H-plasma were changed to investigate the effect of hydrogenation on luminescent properties. Room temperature cathodoluminescence (CL) spectrum showed that hydrogenation can increase the efficiency of UV emission at 3.27 eV, and the improvement is strongly dependent on hydrogenation distances. As the distance was decreased from 90 to 75 mm, the peak intensity of both UV and green emission starts to increase then decrease. For low temperature CL spectrum, the intensity of donor–acceptor pairs (DAP) transition at 3.315 eV has been increased more rapidly after hydrogenation, leading DAP to be the dominant transition. The complex of H with native defects acts as shallow donors, which is an appropriate reason for the improvement of the UV emission efficiency.In the 5th chapter of this dissertation, polycrystalline Zn1-xLixO thin films (0.005≤x≤0.12) were deposited by a sol-gel technique. All the films are in wurtzite structures. CL studies showed that the luminescent efficiency of specimens is degraded sharply with the increment of Li concentration, which indicates that non-radiative centers are introduced during the doping process. The luminescent peaks centered at 3.28 and 3.31 eV are assigned to the LiZn and LiZn-Lii acceptor bound exciton transitions. Ferroelectric properties of Zn1-xLixO thin films (0.08≤x≤0.12) were found from room temperature P-V hysteresis loop measurements, it can be confirmed that the LiZn and LiZn-Lii complex play important roles in the ferroelectric appearance of Li-doped ZnO thin films (0.08≤x≤0.12).更多还原