We report a mask-free technique for the local synthesis of ZnO nanowires (NWs) on polysilicon nanobelts and polysilicon NW devices. First, we used localized joule heating to generate a poly(methyl methacrylate) (PMMA) nanotemplate, allowing the rapid and self-aligned ablation of PMMA within a short period of time (ca. 5 μs). Next, we used ion-beam sputtering to prepare an ultrathin Au film and a ZnO seed layer; a subsequent lift-off process left the seed layers selectively within the PMMA nanotemplate. Gold nanoparticles and ZnO NWs were formed selectively in the localized joule heating region.
Large-aperture vertical-cavity surface-emitting lasers with an equilateral triangular lateral confinement are fabricated to investigate the formation of high-order resonant modes. The experimental lasing patterns are composed of the superscar mode, honeycomb eigenstate, and chaotic mode. Experimental results confirm the theoretical predictions that tiny symmetry breaking can cause the high-order modes to reveal miscellaneous states of integrable and chaotic systems.
The transient dynamics of the eigenstates and coherent states released from a square quantum billiard is analytically and numerically investigated. It is experimentally verified that this transient dynamic can be analogously observed with the free-space propagation of the lasing modes emitted from the laterally confined, vertically emitted cavities. Furthermore, we exploit a chaotically shaped cavity to originally demonstrate the diffraction-in-time characteristics of the chaotic wave functions. It is found that the transient patterns of chaotic wave functions exhibit a striking feature of random branching behavior with the appearance of intricate interference fringes.
We demonstrate experimental generation of two-dimensional (2D) chaotic vector fields from a surface-emitting microcavity laser with precisely control of the operating temperature and the operating current. The 2D optical vector field is found to be formed by frequency locking of two linearly polarized laser modes with different chaotic spatial structures. The eigenfunction expansion method is used to reconstruct the experimental wave function for analyzing the properties of the vector singularities. It is shown that the distribution of vector singularities obeys the sign rule of nearest-neighbor singularities in the phase space of the vector field.
The optical and electrical properties of isoelectronic In-doped GaN films grown by metalorganic vapor phase epitaxy (MOVPE) were investigated by X-ray, photoluminescence (PL), Hall and Raman measurements. As a result, adequate Indoping quantity causes not only a reduction of yellow luminescence and unintentional background concentration, but an enhanced mobility and decrease in the widths. The improved crystalline and optical qualities of GaN films may be attributed to the decrease in defects. ᭧
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