氧化锌薄膜和纳米结构的制备及光电改性研究
文献类型：学位论文
| 作者 | 吴永庆 |
| 学位类别 | 博士 |
| 答辩日期 | 2008 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 徐军 |
| 关键词 | 氧化锌薄膜、生长机制、缺陷发光、掺杂机理、离子束技术、等离子体、纳米阵列、复合材料 |
| 其他题名 | Study on the preparation of ZnO films and nanomaterials and their photoelectric properties modification |
| 中文摘要 | 氧化锌是一种宽带隙化合物半导体，具有六方纤锌矿结构，激子结合能为60meV。ZnO具有良好的透明导电性、压电性、光电性、气敏性、压敏性、且易于与多种半导体材料实现集成化。由于这些优异的性能，ZnO具有广泛的应用前景，引起了国内外科学界及工业界的极大关注。目前，ZnO的p型掺杂依然是限制ZnO应用的瓶颈。研究掺杂的物理机制是解决p型掺杂的基础。本文着眼于ZnO的p型掺杂这一关键问题，围绕ZnO薄膜的生长机制、本征缺陷物理、p型掺杂机理和载流子输运行为展开研究。 分别采用脉冲激光沉积(PLD)方法、超声喷雾热分解(USP)方法和射频磁控溅射方法生长了ZnO薄膜。研究发现PLD法易于获得高结晶质量的单一取向薄膜，对蓝宝石沉积进行预退火处理，可以在其表面形成原子台阶，从而提高ZnO薄膜质量。USP方法成膜粒子能量低，生长薄膜为多晶结构，沉积时间对ZnO薄膜质量的影响与沉积温度类似，在衬底温度为450°C时，沉积时间以40min为宜。用XRD研究了磁控溅射的优化工艺，衬底温度500-700°C，氧气分压0.2-1Pa，在此基础上，研究了Si片上沉积ZnO薄膜的演变过程，分析了薄膜生长机理。离子溅射可以对Si表面进行一定形貌化，在合适剂量的情况下，有助于提高沉积速率，但对Si片表面会有损伤，从而带来应力，因此有必要对其进行退火处理。 研究了退火气氛和温度对氧化锌薄膜光电性能的影响。结果表明，不同气氛 下最佳的退火温度有所不同，如氧气中退火最优温度为600℃，而氩气为700℃，氮气为800℃。高温和低温退火效果并不一样，这主要是由于两种温度下扩散机制不一样造成的。ZnO薄膜的深能级发射经计算得到是由于Zni到VZn的跃迁而导致的绿光发射。H比较容易分解，并容易存在于ZnO的晶粒晶界之间，可以极大提高ZnO薄膜的电学性能。 研究了离子注入对氧化锌薄膜光电性能的影响，离子注入对ZnO薄膜有破坏作用，因此为了得到高质量ZnO薄膜，需要在离子注入之后进行后续退火处理。轻元素如C、H、N等离子注入，与薄膜的相互作用主要表现为溅射效应，且在ZnO薄膜中易于占据间隙位置。采用双离子注入的办法得到了稳定的P型掺杂，其中Li、N共掺得到的p型ZnO，载流子浓度、迁移率分别为3.54×1019 cm-3和619.9 cm2•V-1•s-1，而电阻率仅为0.09Ω•cm。而Ga、N共掺可不经过退火活化即可得到载流子浓度、迁移率和电阻率为1.41×1019 cm-3、1.07 cm2•V-1•s-1和0.4393Ω•cm的p型ZnO薄膜。 以高质量的AAO薄膜为模板或者掩膜，制备了ZnO纳米点阵列，并以之为籽晶层，制备ZnO纳米线或纳米柱，研究了其场发射性能。结果显示，纳米线的场发射性能比纳米柱更加稳定，而且离子辐照能够提高场发射的均匀性和点密度。在600℃下，经氢等离子体处理2小时后的ZnO纳米线场发射开启电压值仅为0.55V•um-1，而其阈值电压约为2.3 V•um-1，达到甚至超过现有碳纳米管或ZnO材料场发射性能。用简单的热蒸发法制备得到ZnO/CNTs复合材料，并研究了复合材料对甲基橙溶液的光催化性能。 |
| 英文摘要 | ZnO is a II-VI compound semiconductor with a wide direct bandgap of 3.37eV at room temperature, exciton binding energy of 60meV. Great attention is given to ZnO from the researchers and the industry around the world due to their excellent physical and chemical properties. ZnO is a promising blue and UV light emitter, but its application is always limited by the p-type bottleneck. A basic understanding of defect physics and doping mechanism is essential and helpful for overcoming the p-type difficulty. In this thesis, we studied the growth mechanism, intrinsic defect physics, p-type doping mechanism and carrier transport behavior for the ZnO film. ZnO films were grown by pulsed laser deposition (PLD), ultrasonic spray paralysis (USP) and rf sputtering deposition respectively. To improve the crystalline of the film by PLD, we proposed pre-treatment to Al2O3 substrate at various temperatures. Atomically flat surface and high density of atomic steps are formed after annealing treatment, which is qualified to be good nucleation sites for ZnO film growth. The deposition time plays the similar roles as deposition temperature when USP is concerned. The suitable deposition time is 40min when the temperature is certain to be 450°C. The parameters of rf magnetic sputtering are studied by XRD. The optimized parameters are substrate temperature of 500-700°C, oxygen pressure of 0.2-1Pa. The growth process of ZnO films by rf MS is investigated by AFM and their growth mechanism is analyzed. Ion beam sputtering can pattern the surface of Si substrate and then enhance the properties of ZnO films. Effects of annealing on properties of ZnO films were investigated. The best annealing temperature varies with the annealing ambient. The optimized temperature with oxygen as annealing ambient is 600℃, N2 800℃ and Ar 600℃. The effects of annealing at various temperatures are different due to the varied diffusion mechanism. The PLD films show a green emission centered at 510nm, assigned as the transition from Zni to VZn. Hydrogen incorporation can enhance the electrical properties of ZnO films. Ion implantation was employed to study the p-type doping of ZnO film by PLD. It is found that ion implantation can bring some damage to ZnO films and annealing treatment is necessary after ion implantation. The main interaction between light ion and ZnO films is sputtering effect. And the light ions are easy to occupy the interval. Stable p-type ZnO are obtained by double-ion implantation such as Ga/N and Li/N codoping。 Highly uniform ZnO nanodot arrays were grown with high quality AAO as template or shuttering and then used as the seed layers to synthesize ZnO nanowire and nanorod arrays. ZnO nanowires show better field emission properties than nanorods. Ion implantation can be introduced to enhance the filed emission properties of ZnO nanowires. The field emission capability of ZnO nanowires treated by hydrogen plasma is impressive. The turn-on field of 0.55V•um-1 and threshold field of 2.3V•um-1can be obtained by H-plasma treatment for 2h at 600℃. The mechanism of field emission was also discussed. ZnO/CNTs materials were prepared by thermal vapor deposition and show good photodegradation for MO solutions. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15224]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 吴永庆. 氧化锌薄膜和纳米结构的制备及光电改性研究[D]. 中国科学院上海光学精密机械研究所. 2008. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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