论文标题:常压MOCVD生长ZnO薄膜的结构和光学性能研究
Structural and Optical Properties Study of ZnO Thin Films Grown by Atmospheric Pressure MOCVD
论文作者
论文导师 江风益；戴江南,论文学位 硕士,论文专业 材料物理与化学
论文单位 南昌大学,点击次数 138,论文页数 73页File Size2875K
2006-05-01论文网 http://www.lw23.com/lunwen_252605462/
ZnO; MOCVD; DCXRD;Photoluminescence;Strain
ZnO是继Ⅲ-Ⅴ族GaN之后制作短波长发光器件的候选材料。目前p-i-n结ZnO-LED已初步实现，但是离实际应用还存在一定的距离。究其原因是晶体质量还有待进一步提高。影响晶体质量的因素很多，如生长工艺、源材料的选择等。不同的工艺和源材料会对ZnO薄膜的性能产生不同的影响。 用MOCVD技术生长ZnO膜仍处于研究初期，特别在源材料的选择上仍在探索之中。目前还没有定论究竟哪种含氧的源材料更适合作ZnO的生长氧源。此外膜内应变会诱导压电场，从而影响将来器件的寿命。所以对这些方面的研究很有必要。本论文主要内容分为以下两个部分： 第一部分：本文采用本实验室自行研制的常压MOCVD系统以c-Al_2O_3为衬底，DEZn为锌源，首先以去离子水(H_2O)和N_2O为氧源，采用三步生长法生长了晶体质量较高的ZnO薄膜为A样品；另外完全以去离子水为氧源生长了高质量的ZnO薄膜为B样品。用X射线双晶衍射和光致发光谱对这两种样品进行表征，比较了它们的结构性能和光学性能，得到了一些有新意的研究结果： 1．用X射线双晶衍射对ZnO薄膜进行了表征。结果表明，以N_2O为氧源生长出了结晶质量较高的ZnO薄膜，其倾斜对称面(10-12)的Omega扫描半峰宽仅为350arcsec。 2．使用低温光致发光谱表征了以N_2O为氧源生长的ZnO膜和以H_2O为氧源生长的ZnO膜的发光特性。结果表明这两种氧源生长的ZnO薄膜的光学性质明显不同，以N_2O为氧源生长的ZnO薄膜的低温PL谱中没有观察到与氢有关的3.331eV双电子卫星峰(TES)。说明以N_2O为氧源生长的ZnO薄膜不易引进氢原子，这将有利于将来的P型掺杂。同时在以N_2O为氧源生长的ZnO薄膜的低温光致发光谱中，我们观察到了ZnO薄膜A自由激子的三级声子伴线。 第二部分：本文采用本实验室自行研制的常压MOCVD系统，以c-Al_2O_3为衬底，DEZn为锌源，去离子H_2O为氧源，用不同的外延温度生长了ZnO薄膜。用X射线双晶衍射和PL谱对其进行了表征，得到了一些有意义的结果： 1．X射线双晶衍射结果为所生长的样品的(0002)面DCXRD ω摇摆曲线半峰宽均低于270arcsec，(10-12)面的ω摇摆曲线半峰宽均小于350arcsec。说明这四个样品不仅是高度c轴择优取向生长，而且属Mosaic(马赛克)结构较好的单晶膜。结果还表明，随
ZnO is a suitable candidate material for short wavelength device after GaN. Applicable ZnO optoelectronic devices have not been fabricated, though p-i-n LED has initially come true. The reason is the quality of ZnO thin film need to be improved ulteriorly. The affected factors of the quality of ZnO thin film have a good many. The different process and source material can affect the properties of ZnO epitaxial layers.It is still in initial stage for ZnO film grown by metal organic chemical vapor deposition, especially it is in grope stage for selection of source materials. It is still disputed Which O precursor fit to grown ZnO on earth. In addition strain can induce piezoelectricity in ZnO film and it will affect the life of device in the future. So it is necessary to carry out these study. The concent of this article consists of two parts:The first part: High-quality ZnO films were grown on C-Al_2O_3 substrate by atmospheric pressure metal organic chemical vapor deposition (AP-MOCVD) technique, using a method of three-step growth. Zn(C_2H_5)_2 and H_2O were used as the Zn and O precursor in both the low and high temperature buffers and nitrous oxide(N_2O) was used as 0 precursor in the main ZnO layer. Then high quality ZnO films were grown, using H_2O as O source entirely. Two samples were analysed by double crystal X-ray diffraction (DCXRD) and PL spectra, respectively. Compared with their structure and optical properties. From which some encouraging results are as follows:1. ZnO film were analysed by double crystal X-ray diffraction (DCXRD). The results indicated that high quality ZnO film had been grown to use N_2O as O precursor. The full widths at half maximum (FWHM) of the (10-12) Omega rocking curves of the ZnO film by double crystal X-ray diffraction (DCXRD) were 350arcsec.2. Compared with the 10K low temperature PL spectra of the H_2O-grown ZnO sample, the two electron satellite(TES) of 3. 331eV in relation to hydrogen was disappeared in that of the NiO-growth ZnO sample. It shows that hydrogen atom is not easily introduced in the N_2O-growth ZnO film. It is in favor of p-type doping in the future. We observed three LO phonon replicas of A free exciton in low temperature PL spectra of the N_2O-growth ZnO
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