Chracterization of strain and composition in InGaN films by photoreflection and Raman scattering

1. 氮化镓薄膜中的应变和电输运参数：我们通过拉曼散射测量e2声子模频率来评估氮化镓薄膜中的平面应变。我们还通过拉曼散射评估了n型GaN薄膜中的载流子浓度和迁移率以及空间分布。p型材料中的载流子浓度可以通过拉曼光谱中观察到的空穴价间带跃迁强度得到。氮化镓薄膜中六边形到立方分量的空间分布：我们通过关注氮化镓拉曼光谱的一个特征来评估其比例及其空间分布。AIGaN和InGaN薄膜的组成：我们首次在Al组成（0-100%）的整个范围内观察到立方AIGaN薄膜的拉曼光谱。我们观察到声子频率对铝含量的各种依赖性，并与理论模型表现出很好的一致性。我们还首次观察到了生长过程中没有厚的GaN缓冲层的六边形- ingan薄膜的拉曼光谱。我们观察到e2 -声子模频率与In含量0-7%呈线性关系。这些结果将可用于成分表征。我们通过吸收和光反射测量来评估带隙能量。根据实验结果评估了In的含量，并与声子频率的拉曼数据进行了比较。用于拉曼微探测和光反射测量的紫外激发系统：我们开发了一种用于拉曼微探测和光反射测量的紫外激发系统。我们通过在谐振拉曼条件下测量Si和GaN的拉曼光谱来测试系统的性能。

1. Strain and electric transport parameters in GaN :We have evaluated in-plane strains in GaN films from a measurement of the E2-phonon mode frequency by Raman scattering.We have also evaluated carrier concentration and mobility in n-type GaN films together with the spatial distribution by Raman scattering.Carrier concentration in p-type materials can be obtained from the intensity of inter-valence band transition of holes observed in Raman spectra.2. Spatial distribution of hexagona1- to cubic-components in GaN films :We have evaluated the ration and their spatial distribution by focusing on a characteristic feature in GaN Raman spectra.3. Composition in AIGaN and InGaN films :We have observed Raman spectra of cubic-AIGaN films for the first time for the whole range of Al composition (0-100%).We have observed various dependences of phonon frequencies on the Al content, and showed a good agreement with a theoretical model.We have also observed for the first time Raman spectra of hexagonal-InGaN films without thick GaN buffer layers in the growth process.We have observed a linear relation of the E2-phonon mode frequency on the In content of 0-7%.These results will be usable for composition characterizations.We have evaluated the bandgap energy by absorption and photoreflection measurements.The In contents were evaluated from the results and compared with Raman data on phonon frequencies.4. UV-excitation system for Raman microprobing and photo-reflection measurements :We have developed a UV-excitation system for Raman microprobing and photo-reflection measurements.We have tested the system performance by measuring Raman spectra of Si and GaN in the resonant Raman condition.