Recombination mechanism of photoluminescence in InN epilayers

• Published in: Solid state communications 2006, Vol.137 (4), p.203-207
• Main Authors: Fu, S.P., Chen, Y.F., Tan, Keewee
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; D. Recombination mechanism; E. Photoluminescence; Exact sciences and technology; Iii-v semiconductors; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics
• ISSN: 0038-1098; 1879-2766
• DOI: 10.1016/j.ssc.2005.11.013

We report an investigation of the recombination mechanism for photoluminescence (PL) in InN epilayers grown by molecular beam epitaxy and metal-organic chemical vapor deposition with a wide range of free electron concentrations from 3.5×10 17–5×10 19 cm −3. We found that the PL spectra are strongly blueshifted with increasing excitation intensity. For all the samples studied, the exponent of the relationship between the integrated PL intensity and the excitation intensity is very close to unity and independent of the temperature. By assuming Gaussian fluctuations of the random impurity potential, calculation based on the ‘free-to-bound’ recombination model can be used to interpret our results very well and it correctly reproduces the development of the total PL peak shift as a function of carrier concentration. It is concluded that the PL transition mechanism in InN epifilms can be characterized as the recombination of free electrons in the conduction band to nonequilibrium holes in the valence band tail.