Technical Insight
Evidence of Luminescence from InN Clusters (Research Review)
Quite surprisingly, in spite of large densities of threading dislocations, InGaN/GaN multiple QWs exhibit strong luminescence intensity at room temperature. And through a detailed study involving PL and PL excitation, Raman scattering and photoconductivity, the authors have found firm evidence of luminescence from InN clusters. Careful examination of the low energy shoulders of the main peak luminescence reveals that the observed separation is in good agreement with the longitudinal optical phonon energy of a pure InN film measured by Raman scattering. A large Stokes-like shift between the emission peak and the absorption edge is also found, which increases with increasing indium content. In addition, after turning off the pumping light, the photoconductivity signal can persist for a very long period of time. All these observations can be explained as a result of localization of self-organized InN clusters within InGaN layers. Y. F. Chen et al, National Taiwan University, Taiwan Appl. Phys. Lett., 2000, 76(25), p. 3712
