Effects of silicon doping on the nanostructures of InGaN/GaN quantum wells

• Published in: Journal of crystal growth 2005-05, Vol.279 (1), p.55-64
• Main Authors: Chen, Meng-Ku, Cheng, Yung-Chen, Chen, Jiun-Yang, Wu, Cheng-Ming, Yang, C.C., Ma, Kung-Jen, Yang, Jer-Ren, Rosenauer, Andreas
• Format: Article
• Language: English
• Subjects: A1. Segregation; A3. Quantum wells; B1. Nitrides; B3. Light emitting diodes; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Doping and impurity implantation in iii-v and ii-vi semiconductors; Electron states; Exact sciences and technology; Iii-v semiconductors; Level splitting and interactions; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Photoluminescence; Physics; Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect; Spin-orbit coupling, zeeman, stark, and strain splitting, jahn-teller effect; Structure of solids and liquids; crystallography
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2005.02.018

We compare the results of strain state analysis (SSA) and photoluminescence (PL) of six InGaN/GaN quantum well samples with un-doped, well-doped, and barrier-doped structures. Based on the SSA images, a strain relaxation model is proposed for describing the nanostructure differences between the three sets of sample of different doping conditions. In the barrier-doped samples, the hetero-structure-induced strains are fully relaxed such that spinodal decomposition is effectively induced. Therefore, strongly clustering nanostructures are observed. In the well-doped samples, strains are partially relaxed and the spinodal decomposition process can be slightly induced. Hence, weaker composition fluctuations are observed. Then, in the un-doped samples, the un-relaxed strains result in higher miscibility between InN and GaN, leading to the relatively more uniform composition distributions. Between the low- and high-indium samples, higher indium content leads to a stronger clustering behavior. The strain relaxations in the well-doped and barrier-doped samples result in their unclear S-shaped behaviors of PL spectral peaks. The enhanced carrier localization and reduced quantum-confined Stark effect in the barrier-doped samples are responsible for their significant increases of radiative efficiency.