【作者】 徐南娟；

【导师】 赵连城； 李洪涛；

【作者基本信息】 哈尔滨工业大学 ， 材料物理与化学， 2008， 硕士

【摘要】 本文用分子束外延法在半绝缘GaAs（001）衬底上成功生长了InSb/InAsSb超晶格薄膜材料,并对薄膜表面形貌、断面形貌、晶体结构、元素扩散和光电性能等进行了研究。对所生长薄膜的能带结构进行模拟计算,结果表明:无论是压应力还是拉应力,均使材料的禁带宽度减小。设计并生长了InSb/InAsSb超晶格薄膜样品,并通过试验方法确定出缓冲层生长工艺参数,结果表明:在570℃、Ga束流为2×10^-7torr时生长的GaAs缓冲层质量较好。采用原子力显微镜观察分析薄膜的表面形貌,结果表明:与420℃相比,在450℃所生长的InAsSb薄膜的表面粗糙度较小,但个别地方有条形缺陷。采用扫描电子显微镜观察薄膜的断面形貌,得出元素分布情况,结果显示薄膜断面从基体到表面的解理条纹连续分布,说明薄膜各层间共格良好。利用双晶X射线衍射方法对薄膜晶体质量进行评价,分析结果显示出了尖锐的衍射峰,表明薄膜的结晶质量良好。采用XPS方法对薄膜的成分分布与元素扩散进行分析,结果表明:薄膜各层间存在元素的扩散,450℃生长的薄膜Ga的扩散层深达100nm左右,As的扩散层深则达到120nm之多。且超晶格InAsSb层中,As:Sb值稍小,不掺杂层中有少量Si扩散。研究还表明在420℃生长的样品中,在超晶格界面处Sb除了有一个纯Sb的峰外,还有Sb-As共价键的峰,且超晶格中As也发生了一定的扩散。采用红外吸收光谱法对样品的红外吸收性能进行分析,结果表明在10¹7μm长波段薄膜红外响应性能良好。使用霍尔测试方法对样品的电学性能如迁移率、载流子浓度等进行测试,结果显示:随着温度升高,电子扩散程度和载流子浓度增大,表面电阻率减小,霍尔系数变小;在室温下和在液氮温度下材料的迁移率差别不大。更多还原

【Abstract】 Molecular Beam Epitaxy (MBE) method has been used to grow InSb/InAsSb SLS epitaxial layer on GaAs (001) substrate.Furthermore, surface appearance, cross-surface appearance, crystal structure, diffusion of elements and photoelectric properties were studied.The Eg of each layer was calculated by using quantum mechanics calculator of simulation software of Materials Studio. The results indicated that the Eg of the material was lessened either pressed or pulled,which laid a theoretical foundation for the design of the film structure.We also designed two film samples and growed them using MBE method.Moreover,the parameter of growth condition of buffer layer and epitaxial layer was also given from experimentation.The results showed that buffer layer of GaAs had a good performance when growed at 570℃and pressure of Ga was 2x10-7torr.Atomic force microscope (AFM) was used to research the surface appearance.The results showed surface roughness of InAsSb film growed at 450℃was smaller compared with the one growed at 420℃, but some places had strip flaws. Scan electron microscope (SEM) was used to research the cross-surface appearance.Distribution of elements was achieved.The results showed that cleavage stripes of cross-surface from epitaxial layer to the surface of the substrate distributed continuously,which indicated each layers of the film matched well. The crystal quality of specimen has been investigated by means of double crystals X-ray diffraction (DXRD).The sharp diffraction apices showed in the result indicated the crystal quality of the film was comparatively good. The distributing and diffusing of film component was studied by means of XPS method.The results showed there were diffusing of elements between layers of the film. As for specimen growed at 450℃, diffusing depth of Ga was as deep as 100nm, which of As was round about 120nm. Moreover,the value of As:Sb was a bit small in the SLS layer,and a few Si was diffused in the undoped layer. There were peak of Sb-As covalent bond apart from peak of pure Sb as for specimen growed at 420℃,and As in the superlattice was diffused. The method of Infrared absorption spectrum was adopted to investigate optic capability of the specimen.The results indicated that infrared responding ability of the specimen was good when wave range was about 10~17μm. The Electric behavior was researched by Hall effect measurement.The results showed that as the temperature increased, e-diffusion level and carrier concentration improved, surface resistivity decreased and Hall coefficient got smaller. The electric behavior of specimen made no obvious difference at 300K compared with 77K.更多还原