Both monoclinic Ga 2 O 3 and Wurtzite-structured GaN are wide-band-gap semiconductors (energy gap, E g = 4.9 eV and 3.39 eV, respectively) that exhibit luminescence and conduction properties, thus, they have potential applications in optoelectronic devices, [1][2][3][4][5][6][7][8] high-temperature stable gas sensors, [9] and high-temperature/high-power electronic devices. [10,11] The future of full-colored, flat panel displays, blue lasers, and optical communication is likely to be based on GaN. [5,12] Nanostructured Ga 2 O 3 and GaN with varied morphology, for instance, nanoparticles, [13] nanorods, [14] nanowires, [3,15] nanobelts, [4,16] and nanotubes [5][6][17][18] have been prepared. However, monodispersed spherical structures of the two semiconductor compounds have not been prepared up to now.
Monodispersed micro-or nanospheres, as a kind of competitive building blocks for future nanodevices, have become a new focus of research. This interest has arisen because it is now relatively easy to synthesize uniform spheres and to control their size, and these spheres can self-assemble into 2D or 3D colloidal arrays or photonic band gap crystals. [19][20][21][22][23] The preparation of uniform micro-or nanospheres of semiconducting materials would enable their use as building blocks for new photonic crystals or as model systems for light scattering, which are of both theoretical and practical significance. New approaches to semiconductor hollow spheres have been made in the last five years. [24][25][26][27][28][29][30][31][32][33] Semiconducting oxide ceramic hollow spheres (e.g., TiO 2 , SnO 2 ) have been prepared by templating the sol-gel precursor solutions with monodispersed latex beads. [24] By alternating the shape and structure of the templates, the morphology of hollow structures can also be changed. [25,26] The II-VI family of semiconductor luminescent nanoparticles, such as CdTe, CdS, ZnS, have been assembled on spherical templates to form luminescent shells by using a layer-by-layer selfassembly strategy, [27][28][29] sonochemical deposition, [30] or chemical-bath deposition. [31][32] Very recently, our group has developed a solution-based template-free route to ZnSe semiconducting hollow spheres by condensing ZnSe nanoparticles on a liquid-gas interface. [33] Herein, we report the application
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