SELECTIVE GROWTH OF III-NITRIDE MICROSTRUCTURES ON SILICON SUBSTRATE

采用iii -氮化物金属-有机气相外延（MOVPE）中的选择性面积生长方法（SAG），在特定晶面上生长了GaN/AlGaN和InGaN/GaN微纳米异质结构。研究发现，硅衬底AlN中间层的形成过程和性能对iii -氮化物的后续生长起着至关重要的作用。我们已经获得了一个无裂纹的单晶，直径为200-500微米。发现化学物质在气相和表面的扩散过程对合金的成分和层厚的确定起着重要的作用。详细讨论了镓的表面间扩散作用。（1-101） GaN的生长是在7度差取向（001）硅衬底上进行的。通过降低轴向，我们首次实现了无裂纹和极平坦的n形表面。由于界面平坦，InGaN/GaN双异质结构的光学性质呈现出锐利的边缘发射。使用该材料，我们实现了一个具有极低的光损耗的近波段边缘波长的光波导。用飞秒光谱法研究了激子的光谱和衰减过程，发现减小点/盘的尺寸可以降低激子的衰减速率。提出了用氢化物气相外延（HyPE）生长厚氮化镓的方法。使用厚MN中间层，我们在（111）Si上获得了均匀的23微米厚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.