GaN/Al₂O₃（0001）大晶格失配异质结构的PAMOCVD外延生长

【作者】 曲钢；

【导师】 徐茵；

【作者基本信息】 大连理工大学 ， 材料物理与化学， 2004， 硕士

【摘要】 GaN作为第三代半导体材料，因其优良的特性，日益成为研究的热点，在微电子和光电子领域具有十分广阔的应用优势和发展前景。 本论文采用电子回旋共振（ECR）微波等离子体辅助金属有机物化学气相沉积（PAMOCVD）方法，以氮等离子体为氮源，研究了大晶格失配（14％）异质结GaN/Al₂O₃（0001）的低温（700℃）外延生长。为了释放因晶格失配产生的应力，以降低在GaN外延膜中引起的缺陷密度，我们对蓝宝石衬底采用了氢等离子体清洗、氮等离子体氮化以及低温生长缓冲层的方法。我们用X射线衍射（XRD）来表征晶体的结构，用原子力显微镜（AMF）来表征表面形貌。通过高能电子衍射仪（RHEED）、对实验结果进行分析比较，对GaN薄膜的清洗、氮化、缓冲层和外延生长实验参数进行了优化。XRD和AFM的结果表明，我们在蓝宝石衬底上获得了晶质良好的GaN薄膜。实验中采用了氢氮混合等离子体清洗的方法，提高了清洗的质量。文中讨论了氮化层的原子排列点阵相对于蓝宝石衬底（0001）面旋转了30°的机理；解释了在六方相的缓冲层上在较低温度下外延生长GaN的过程中出现立方相GaN的现象。另外，在分析实验流程的特点的基础上，对ESPD-U半导体薄膜生长实时监控系统作了改进。更多还原

【Abstract】 GaN, one of the third generation semiconductor materials, becomes the hot point of research because of its excellent characteristics. It has wide potential application and development in the fields of microelectronics and optoelectronics.This dissertation presents the investigation on the epitaxy growth with large lattice mismatch (14%) heterostructures GaN/Al2O3(0001), by an electron cyclotron resonance (ECR) plasma assisted metalorganic chemical vapor deposition (PAMOCVD) with a nitrogen plasma as a nitrogen source at low temperature (700℃) . In order to release the stresses originated from the lattice mismatch and reduce the defect densities, sapphire substrate surfaces are preprocessed by H-plasma cleaning , N-plasma nitriding and the low temperature buffer growth. The film crystal structure is characterized by XRD and the film surfaces morphology is observed by AFM. The Growth parameters were optimized and an ideal growth conditions have been got finally by comparing the results of RHEED. The result of XRD and AFM indicates that high quality GaN films were grown on sapphire. A better result is got when cleaning sapphire by hydrogen and nitrogen plasma. The mechanism of the 30?rotation of (0001) nitride plane produced by the nitridation with respect to the (0001)Al2O3 is discussed. We observed that zinc blende GaN epilayer can grow on the wurtzite GaN buffer at low temperature and give a logical explanation to it. Additionally, the real-time monitoring system of semiconductor film growth for the ESPD - U device is improved according to the characteristics of the growth procedure .更多还原