Browsing by Author "Hsiao, Ching-Lien"

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Growth of sparse arrays of narrow GaN nanorods hosting spectrally stable InGaN quantum disks
(2012-07-16)
Chen, Yen-Ting
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Tsai, Wen-Che
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Chen, Wen-Yen
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Hsiao, Ching-Lien
;
Hsu, Hsu-Cheng
Wafer-scale production of single InGaN quantum disks (QD) in-a-nanorod array with small rod diameter (> 9 nm) and low rod-density (< 10(8) cm(-2)) has been achieved without extensive processing steps. Excitation power-dependent mu PL spectrum of single QD reveals multi-excitonic peak with 0.75 meV blue-shift for 3 orders of magnitude increasing power, indicating the present system is spectrally stable and nearly free of quantum-confined Stark effects, due possibly to the strain relaxation induced by free surface of small rod diameters. The fully polarized emissions, a high working temperature (180 K), low rod density and good alignment, render this system promising as a potential quantum photon source. (C) 2012 Optical Society of America
Selective-area growth of single-crystal wurtzite GaN nanorods on SiOx/Si(001) substrates by reactive magnetron sputter epitaxy exhibiting single-mode lasing
(2017-10-05)
Serban, Elena Alexandra
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Palisaitis, Justinas
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Yeh, Chia-Cheng
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Hsu, Hsu-Cheng
;
Tsai, Yu-Lin
Selective-area growth (SAG) of single-crystal wurtzite GaN nanorods (NRs) directly onto Si(001) substrates with un-etched native SiOx amorphous layer, assisted by a patterning TiNx mask fabricated by nanosphere lithography (NSL), has been realized by reactive magnetron sputter epitaxy (MSE). The GaN NRs were grown vertically to the substrate surface with the growth direction along c-axis in the well-defined nano-opening areas. A 5-step structural and morphological evolution of the SAG NRs observed at different sputtering times depicts a comprehensive growth model, listed in sequence as: formation of a polycrystalline wetting layer, predominating c-axis oriented nucleation, coarsening and coalescence of multi-islands, single NR evolution, and finally quasi-equilibrium crystal shape formation. Room-temperature cathodoluminescence spectroscopy shows a strong GaN bandedge emission with a uniform luminescence across the NRs, indicating that the SAG NRs are grown with high quality and purity. In addition, single-longitudinal-mode lasing, attributed to well-faceted NR geometry forming a Fabry-Perot cavity, was achieved by optical pumping, paving a way for fabricating high-performance laser optoelectronics using MSE.