title: Nanoscale optical properties of indium gallium nitride/gallium nitride nanodisk-in-rod heterostructures.
abstract: III-nitride based nanorods and nanowires offer great potential for optoelectronic applications such as light emitting diodes or nanolasers. We report nanoscale optical studies of InGaN/GaN nanodisk-in-rod heterostructures to quantify uniformity of light emission on the ensemble level, as well as the emission characteristics from individual InGaN nanodisks. Despite the high overall luminescence efficiency, spectral and intensity inhomogeneities were observed and directly correlated to the compositional variations among nanodisks and to the presence of structural defect, respectively. Observed light quenching is correlated to type I1 stacking faults in InGaN nanodisks, and the mechanisms for stacking fault induced nonradiative recombinations are discussed in the context of band structure around stacking faults and Fermi level pinning at nanorod surfaces. Our results highlight the importance of controlling III-nitride nanostructure growths to further reduce defect formation and ensure compositional homogeneity for optoelectronic devices with high efficiencies and desirable spectrum response.
authors: †Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors: Xiang
authors: X
authors: Zhou
authors: ‡Graduate Institute of Opto-Mechatronics, National Chung Cheng University, Chia-Yi 62102, Taiwan.
authors: Ming-Yen
authors: MY
authors: Lu
authors: §Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors: Yu-Jung
authors: YJ
authors: Lu
authors: †Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors: Eric J
authors: EJ
authors: Jones
authors: §Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors: Shangjr
authors: S
authors: Gwo
authors: †Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors: Silvija
authors: S
authors: Gradečak
keywords: III-nitrides; cathodoluminescence; nanorods; nanowires; optical properties