SELECTIVE GROWTH OF III-NITRIDE MICROSTRUCTURES ON SILICON SUBSTRATE

采用金属-有机气相外延(MOVPE)中的选择性区域生长法(SAG)，在特定的晶面上生长了GaN/AlGaN和InGaN/GaN微纳异质结。研究发现，硅衬底上AlN中间层的形成过程和性质对后续III-氮化物的生长起着至关重要的作用。我们已经实现了直径为200-500微米的无裂纹单晶。研究发现，化学物种在气相和表面的扩散过程对决定合金的成分和层厚度起着重要作用。详细讨论了界面扩散对(1-101)GaN生长的影响，并在(001)硅衬底上生长了(1-101)GaN。通过倾斜轴线，我们首次获得了无裂纹和非常平坦的N表面。由于界面平坦，InGaN/GaN双异质结的光学性质表现出锐利的边缘发射。利用这种材料，我们得到了近带边波长具有极低j光学损耗的光波导。用飞秒光谱研究了激子的光谱和衰变过程，发现随着点/盘尺寸的减小，激子的衰变速率降低。将氢化物气相外延(HYPE)方法发展到厚GaN的生长。使用厚的MN中间层，我们在(111)Si上获得了均匀的23微米厚的GaN层。

Adopting the selective area growth method (SAG) in the metal-organic vapor phase epitaxy (MOVPE) of III-nitrides, we have developed the growth of GaN/AlGaN and InGaN/GaN micro-and nano-heterostructure on specific crystal facets. It was found that the formation process and properties of the AlN intermediate layer on the silicon substrate has the essential role to the following growth of III-nitrides. We have achieved a single crystal free from cracks with the size of 200-500 micron across. The diffusion processes of the chemical species in the gas phase and on the surface were found to give an important role to determine the composition of the alloy as well as the layer thicknesses. The role of the inter-surface diffusion of Ga was discussed in detail.The growth of (1-101) GaN was performed on a 7 degree off oriented (001) silicon substrate. By declining the axis, we achieved crack free and extremely flat N-surface for the first time. Because of the flat interface, the optical properties of an InGaN/GaN double heterostructure exhibited a sharp edge emission. Using the material we achieve a optical waveguide with extremely low j optical loss for the near band edge wavelengths. Optical spectra and decay processes of excitons were investigated with femto-second spectroscopy and it was found that the decay rate is decreased by reducing the size of dot/disk.The method was developed to the growth of a thick GaN by hydride vapor phase epitaxy (HyPE). Using a thick MN intermediate layer, we achieved a uniform 23 micron thick GaN layer on (111)Si.