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题名	氧化镓晶体的掺杂与电学性能调控研究
作者	周威
文献子类	硕士
导师	夏长泰
关键词	β-Ga2O3 β-Ga2O3 Nb:β-Ga2O3 Nb:β-Ga2O3 Ta:β-Ga2O3 Ta:β-Ga2O3 光学浮区法 optical floating zone method
其他题名	Research on controlling the conductivity of β-Ga2O3 by doping
英文摘要	氧化镓(β-Ga2O3)是一种新型直接带隙宽禁带半导体材料，具有禁带宽度大(4.9 eV)，击穿场强高(8 MV/cm),可用熔体法直接生长大尺寸单晶等优点。近年来，氧化镓开始在功率电子器件及深紫外光电子器件领域展示出巨大的应用前景，已成为科学研究的热点方向之一。 作为半导体材料，电学性能调控是材料性能研究的关键分支，目前氧化镓n型载流子的掺杂调控方案仍然有一定的局限性。针对这一问题，本文结合前期研究成果，在理论计算的基础上，选取高价Nb和Ta离子进行掺杂，探索氧化镓n型导电性新型调控方案，并研究了掺杂对氧化镓单晶性能的影响。主要研究内容包括以下几个方面： 1. 采用光学浮区法生长了高质量纯β-Ga2O3单晶，晶体双晶摇摆曲线半高宽只有83弧秒。经过精细抛光，晶体表面粗糙度(RMS)仅为0.15 nm。 2. 采用光学浮区法生长了不同掺杂浓度的Nb:β-Ga2O3单晶，研究了掺杂对晶体电学性能的影响，结果显示晶体的电阻率随着掺杂浓度的增加而降低，由3.6×102 Ω·cm减小到5.5×10-3 Ω·cm，载流子浓度随掺杂浓度的升高而升高，从9.55×1016 cm-3增加到1.8×1019 cm-3，表明Nb可以作为一种有效的n型掺杂元素来调控β-Ga2O3单晶的电学性能。测试分析了Nb:β-Ga2O3单晶的透射光谱，发现由于载流子浓度的变化导致晶体在红外区的透过率随着掺杂浓度的升高而降低。 3. 通过荧光光谱、深能级瞬态谱以及热释光研究了Nb:β-Ga2O3晶体的缺陷特性。发现荧光光谱中的蓝色发光随着Nb掺杂浓度的升高而降低，这是由于载流子浓度的升高导致晶体内VO的形成能增大，VO和VO-VGa的浓度减小，导致蓝色荧光的发射强度减弱。深能级瞬态谱(DLTS)测试发现了一个距导带底0.70 eV的深能级缺陷，认为它是氧空位导致的深能级缺陷，其浓度为5.59×1014 cm-3，热释光测试也证实了该缺陷。 4. 使用光学浮区法生长了不同掺杂浓度的Ta:β-Ga2O3单晶，并测试研究了晶体的电学性能和光学性能。结果显示Ta:β-Ga2O3晶体的载流子浓度随掺杂浓度的升高而升高，而迁移率由于电离散射的增强而降低。透射光谱显示由于载流子浓度的升高导致Ta:β-Ga2O3单晶在红外区的透过率降低。深能级瞬态谱(DLTS)测试发现一个与Nb:β-Ga2O3类似的激活能为0.73 eV深能级缺陷，其浓度为3.67×1014 cm-3。拉曼光谱测试发现Ta:β-Ga2O3单晶位于770 cm-1附近的拉曼峰强度几乎为零，位于310-480 cm-1附近的拉曼峰相比于未掺杂晶体略有增强，推测Ta可能主要进入了[GaO6]八面体。; Gallium oxide (β-Ga2O3) crystal is a new direct-band-gap semiconductor material. It has a bandgap of ~4.9 eV, a high breakdown field of ~8 MV/cm, and can be grown in bulk form from melt. In recent years, it has showed great prospects in the field of Ga2O3-based electronic devices and deep ultraviolet optoelectronic devices, and gallium oxide has become one of hot topics in scientific research. In most application fields, the electrical properties of Ga2O3 substrates are of critical importance. In this thesis, Nb and Ta are chosen to explore novel n-type conductivity based on previous research and theoretical calculations. The main conclusions are as follow: 1. High-quality β-Ga2O3 single crystal was grown by the optical floating zone method. The rocking curve showed that half-width is only 83 arc sec. And the surface roughness of the crystal is only 0.15 nm after fine polishing. 2. β-Ga2O3 single crystals with different Nb doping concentrations were grown by the optical floating zone method. The electrical properties of the crystals were studied. The results showed that the electrical resistivity can be varied from 3.6×102 Ω·cm to 5.5×10-3 Ω·cm by increasing the Nb doping concentration, and the related free carrier concentration increase from 9.55×1016 cm-3 to 1.8×1019 cm-3. It is evident that Nb can be an effective n-type dopant. The transmission spectrum of Nb:β-Ga2O3 was measured. The transmittance of Nb-doped β-Ga2O3 crystals in the infrared region (IR) region diminishes with the increasing Nb concentration. 3. The defects of Nb:β-Ga2O3 crystals were studied by photoluminescence spectra, thermoluminescence spectra and deep level transient spectroscopy. The blue photoluminescence decreases with the increasing Nb concentration, because the increase of carrier concentration leads to the formation of VO increases. Therefore, the concentration of VO and VO-VGa decrease and blue emission decreases. The Deep level transient spectroscopy (DLTS) measurement was performed and a defect state was detected at EC-0.70 eV, which should be oxygen vacancies, and the concentration is 5.59×1014 cm-3. And the defect was detected by thermoluminescence spectra. 4. β-Ga2O3 single crystals with different Ta doping concentrations were grown by optical floating zone method, and the electrical and optical properties were studied. The carrier concentration in Ta:β-Ga2O3 single crystals increase with the increasing doping concentration, and the mobility decreases due to ionization scatting. The transmittance of Ta:β-Ga2O3 crystals in the IR region decreases with the increasing Ta concentration. Like Nb-doped β-Ga2O3 crystals, a defect state was detected at EC-0.73 by DLTS and the concentration was 3.67×1014 cm-3. In the Raman spectra the intensity of the Raman peak at 770 cm-1?? is almost zero due to Ta doping, and 310-480 Raman peaks increased. It suggests that Ta is easier to substrate Ga in [GaO6] octahedron according to the Raman characteristics of β-Ga2O3.
学科主题	材料学
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/31113]
专题	中国科学院上海光学精密机械研究所
作者单位	中国科学院上海光学精密机械研究所
推荐引用方式 GB/T 7714	周威. 氧化镓晶体的掺杂与电学性能调控研究[D].

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