SELECTIVE GROWTH OF III-NITRIDE MICROSTRUCTURES ON SILICON SUBSTRATE

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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.