ZnO基薄膜的掺杂、异质结制备与应用研究

发布时间：2018-04-05 15:08

本文选题：ZnO薄膜　切入点：ZnMgO薄膜　出处：《浙江大学》2015年博士论文

【摘要】：ZnO室温下的禁带宽度为3.37 eV,吸收边位于紫外波段,在可见光区透明,与MgO合金化得到的更宽禁带的ZnMgO薄膜可应用在深紫外光电器件中。掺入A1、Ga和F等施主掺杂剂可以有效地改善ZnO的本征n型导电性能。科技的进步促使电子器件朝柔性化、超薄化方向发展,迫切需要发展柔性透明导电材料。因此,制备柔性透明导电ZnO基材料具有非常重要的现实意义。在本论文中,我们采用脉冲激光沉积技术(PLD, Plused Laser Deposition)制备了F掺杂ZnMgO (ZMOF)透明导电薄膜,此外,为了满足柔性器件的应用要求,我们还开展了柔性；ZMOF透明导电薄膜的研究。由于制备高质量、可重复并稳定存在的p型ZnO仍是一个难点,导致ZnO同质结器件的制备困难,因此,选用p型NiO与n型ZnO制备的ZnO基异质结器件受到广泛关注。在ZnO/NiO异质结的基础上,我们通过调节Mg含量来制备不同禁带宽度的Ni1-xMgxO薄膜,与ZnO和ZnMgO制备成异质结器件并深入研究其能带结构。1.采用PLD方法在石英衬底上制备了ZMOF薄膜。350。C,0.001 Pa条件下制备的ZMOF薄膜(3 at.%的F,10 at.%的Mg)具有最好的光电性能,电阻率最低为6.92×10-4 Ωcm,在整个可见光区的透过率超过85%,且用湿法腐蚀方法制备了绒面ZMOF薄膜。2.利用PLD技术在柔性衬底上制备了ZMOF薄膜,通过引入ZnO缓冲层,提高了薄膜晶体质量,消除了裂纹,电阻率从1.55 Ωcm降低到1.70x10-2Ωcm,迁移率从0.573 cm2V-1s-1升高到11.7 cm2V-1s-1,大大提高了其电学性能。3.利用磁控溅射仪器对以F掺杂ZnO (FZO)为代表的ZnO基薄膜进行了真空退火和H等离子体处理。处理后的FZO薄膜结晶质量更好,电学性能更优,尤其是迁移率实现了3-10倍的增长。我们通过第一性原理计算研究了H在FZO中的位置及能态,发现在ZnO晶格中靠近Fo的间隙位的氢(Hi-Fo)和处于氧空位中的氢(H-Vo)都可以稳定存在,这是H处理后FZO透明导电薄膜高导电性、高热稳定性的原因。4.利用PLD技术生长了一系列不同Mg含量的Ni1-xMgxO薄膜,且制备了可探测日盲区的光导型光电探测器。通过快速退火处理提高了薄膜晶体质量,降低了器件暗电流。为了探讨Mg的引入对ZnO/NiO异质结能带结构的影响,我们制备了不同Mg含量的ZnO/Ni1-xMgxO异质结,通过X射线光电子能谱方法研究了异质结的能带结构。研究发现,Mg含量越高,导带带阶和价带带阶偏移量均越大,导带带阶移动量更大。我们进一步开展了双边带隙可调节的Zn1-XMgxO/Ni1-yMgyO异质结的能带结构研究,发现含有相同Mg组分的ZnMgO和NiMgO, Mg对两者能带调节的作用幅度不同,在ZnMgO中的能带调节作用更为明显。因此,我们可以通过分别调节Zn1-XMgxO/Ni1-yMgyO异质结中的Mg含量,来改变双边的禁带宽度及价带顶、导带底的位置,进而设计出所需能带结构的异质结,灵活掌控其在光电器件中的应用。
[Abstract]:The band gap of ZnO is 3.37 EV at room temperature, and the absorption edge is in the ultraviolet band. The wider ZnMgO films alloyed with MgO can be used in deep ultraviolet optoelectronic devices.The intrinsic n-type conductivity of ZnO can be effectively improved by adding donor dopants such as A _ 1, Ga, F and so on.Advances in science and technology promote the development of electronic devices in the direction of flexibility and thinning. It is urgent to develop flexible transparent conductive materials.Therefore, the preparation of flexible transparent conductive ZnO based materials has very important practical significance.In this thesis, we have prepared F-doped ZnMgO (ZMOF) transparent conductive thin films by pulsed laser deposition technique (PLD, Plused Laser deposition). In addition, in order to meet the application requirements of flexible devices, we have also carried out the research of flexible ZMOF transparent conductive thin films.Due to the difficulty of preparing high quality, repeatable and stable p-type ZnO, it is difficult to fabricate ZnO homojunction devices. Therefore, the ZnO based heterojunction devices fabricated by p-type NiO and n-type ZnO have attracted wide attention.On the basis of ZnO/NiO heterojunction, Ni1-xMgxO thin films with different bandgap were prepared by adjusting mg content. Heterojunction devices were fabricated with ZnO and ZnMgO.ZMOF thin films prepared on quartz substrates by PLD method have the best optoelectronic properties. The ZMOF films prepared at 3.350.Cn0. 001 Pa have the best optoelectronic properties.The lowest resistivity is 6.92 脳 10 ~ (-4) 惟路cm, and the transmittance in the whole visible region is more than 850.Furthermore, the suede ZMOF film .2is prepared by wet etching method.ZMOF thin films were prepared on flexible substrates by PLD technique. By introducing ZnO buffer layer, the crystal quality of the films was improved and the cracks were eliminated. The resistivity decreased from 1.55 惟 cm to 1.70x10-2 惟 cm, and the mobility increased from 0.573 cm2V-1s-1 to 11.7 cm-2 V-1s-1, which greatly improved the electrical properties of the films.F doped ZnO / FZO thin films were annealed in vacuum and treated by H plasma with magnetron sputtering instrument.The treated FZO films have better crystallization quality and better electrical properties, especially the mobility increases 3-10 times.We have studied the position and energy states of H in FZO by first-principles calculation. It is found that both the H ~ (2 +) -H _ (-Fo) and H _ (H _ (H) -Vo) exist stably in the ZnO lattice near the gap potential of Fo and in the oxygen vacancy.This is the reason for the high conductivity and high thermal stability of FZO transparent conductive films after H treatment.A series of Ni1-xMgxO thin films with different mg content were grown by PLD technique, and photoconductive photodetectors with detectable diurnal blind area were fabricated.Through rapid annealing, the quality of thin film crystal is improved and the dark current of the device is reduced.In order to investigate the influence of mg on the energy band structure of ZnO/NiO heterojunction, ZnO/Ni1-xMgxO heterostructure with different mg content was prepared. The band structure of ZnO/Ni1-xMgxO heterojunction was studied by X-ray photoelectron spectroscopy (XPS).It is found that the higher the mg content, the greater the migration of the conduction band order and the valence band order, and the greater the movement of the conduction band order.We have further studied the band-gap tunable Zn1-XMgxO/Ni1-yMgyO heterostructures. It is found that ZnMgO and NiMgO with the same mg component have different amplitudes of energy band regulation, especially in ZnMgO.Therefore, by adjusting the mg content in Zn1-XMgxO/Ni1-yMgyO heterojunction, we can change the band gap and the position of the top and bottom of the conduction band respectively, and then design the heterojunction with the required energy band structure, and control its application in optoelectronic devices flexibly.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB383.2

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