Multiphonon Raman scattering in GaN nanowires

Abstract

UV Raman scattering studies show longitudinal optical (LO) mode up to fourth order in wurtzite GaN nanowire system. Fröhlich interaction of electron with the long range electrostatic field of ionic bonded GaN gives rise to enhancement in LO phonon modes. Good crystalline quality, as indicated by the crystallographic as well as luminescence studies, is thought to be responsible for this significant observation. Calculated size dependence, incorporating size corrected dielectric constants, of electron-phonon interaction energy agrees well with measured values and also predict stronger interaction energy than that of the bulk for diameter below ∼3nm.

Double strain state in a single GaN/AlN nanowire: Probing the core-shell effect by ultraviolet resonant Raman scattering

“…Raman spectroscopy has previously been applied to study the material properties in self-assembled GaN NWs such as the crystal structure, composition, orientation, mechanical strain, doping, and phonon confinement. [10][11][12][13] One of the main results is the strong influence of the large surfaceto-volume ratio in NWs on the electronic and vibrational properties. Very recently, structural properties of GaN/AlN core-shell nanocolumn heterostructures have been investigated by a combination of different techniques including Raman spectroscopy.…”

Optical and structural characterisation of epitaxial nanoporous GaN grown by CVD

“…Under conventional visible excitation (non-resonant), the Raman spectrum of GaN can be masked by the Raman spectrum arising from the substrate; therefore, in order to selectively excite the top GaN layers, UV excitation is necessary, thus working under resonant conditions, which introduces relevant changes in the spectrum. Under these conditions, the polar A 1 (LO) mode allowed for backscattering on the (0001) plane is dramatically enhanced due to the Fröhlich interaction [13,14]. Instead, the non-polar E 2 (high) mode is not enhanced and it appears very weak because of the small scattering volume with UV excitation.…”

Polar interface optical phonon states and their dispersive properties of a wurtzite GaN quantum dot: quantum size effect

“…Thanks to the excellent characteristics of wide band-gap, strong atomic bonding and high electronic mobility as well as high optical efficiency, GaN-based semiconductor materials are quite attractive materials as a basis for the creation of reliable high-power or high-temperature electronic equipment and short wave-length optoelectronic devices [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Following this trend, the investigations on various physical properties of nitride semiconductor low-dimensional quantum structures, such as quasi-2-dimensional (Q2D) quantum wells (QWs) [2][3][4][5][6][7][8], quasi-1-dimensional (Q1D) quantum wires (QWRs) [9][10][11][12][13][14][15][16] have become a hot topic.…”

“…Following this trend, the investigations on various physical properties of nitride semiconductor low-dimensional quantum structures, such as quasi-2-dimensional (Q2D) quantum wells (QWs) [2][3][4][5][6][7][8], quasi-1-dimensional (Q1D) quantum wires (QWRs) [9][10][11][12][13][14][15][16] have become a hot topic. Among these research attempts, the crystal lattice dynamical properties of GaN-based quantum structures have attracted special attention both from theoretical and experimental viewpoint [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. The driving force behind these efforts lies in the evident fact that lattice vibrations have an important effect on the optoelectronic and electronic properties of nitride low-dimensional quantum systems [6][7][8][9][10][11][12][13].…”

“…Among these research attempts, the crystal lattice dynamical properties of GaN-based quantum structures have attracted special attention both from theoretical and experimental viewpoint [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. The driving force behind these efforts lies in the evident fact that lattice vibrations have an important effect on the optoelectronic and electronic properties of nitride low-dimensional quantum systems [6][7][8][9][10][11][12][13]. In fact, the phenomena of phonon replicas in the emission spectra, the homogeneous broadening of excitonic line width and the relaxations of hot carriers to the fundamental band edge are directly related to the lattice vibration of nitride materials [14].…”