Nano-structure Studies on Silicon-doped InGaN/GaN Quantum Wells

• Main Authors: En-Chiang Lin, 林恩強
• Other Authors: C. C. Yang
• Format: Others
• Language: en_US
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/07144763904386556335

碩士 === 國立臺灣大學 === 電子工程學研究所 === 91 === In this research, we study the microstructures of Si-doped InGaN/GaN multiple quantum wells (MQWs) with various doping conditions, including un-doped, well-doped, and barrier-doped conditions. In all the samples, the MQW geometries are the same. Also, the Si doping concentrations are the same in all samples. Two sets of samples of low and high nominal contents are prepared for comparison. One more barrier-doped sample of a medium indium content is also grown for observing the dependence of indium content. High-resolution transmission electron microscopy (HRTEM) images are obtained to show that different shapes of quantum-dot like clusters are formed. Also, different degrees of the interface fluctuation are observed. From digital analysis of lattice images (DALI) of high-indium-content samples, we can clearly see the differences of microstructure between the samples of different doping conditions. Typically, more clusters are formed in Si-doped samples, particularly in the barrier-doped sample. Optical measurements show that with Si-doping, the recombination efficiency can be improved. Such an improvement can be attributed to stronger carrier localization (more clusters formed) and better strain relaxation (weaker quantum-confined stark effect) upon silicon doping, particularly doping in barriers.