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Proceedings Paper

Fabrication and lasing characteristics of GaN nanopillars
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Paper Abstract

We report the fabrication of GaN nanopillars and their laser action characteristics under optical pumping measurement. The nanopillars were fabricated from a GaN epitaxial wafer by self-assembled Ni nanomasked etching, followed by epitaxial regrowth to form crystalline facets on the etched nanopillars. The regrowth process is intended to reduce surface defects created during ICP-RIE etching. The density of etched GaN nanopillars is about 8.5x108/cm2 and the diameter and height of GaN nanopillars are about 250 nm and 650 nm, respectively. The as grown GaN nanopillars exhibit a random distribution with hexagonal pillar geometry. The sample is optically excited by frequency tripled Nd:YAG pulsed laser. The Gaussian waist of pumping spot is 1.8 um. At low pumping intensity, the emission has a broad spontaneous emission spectrum with maximum at 363 nm. As pump intensity increases, a narrow peak at 363 nm emerges quickly from the broad spontaneous emission back ground. The lasing action occurs at threshold pump power density of 122 MW/cm2. The emission linewidth decreases with pumping power across threshold and reaches a lowest value of about 0.38 nm above threshold. The excitation-power-dependent spectra show that the lasing wavelength has a slight blue shift as pump power increases. We remark that this is due the band filling of the increasing excited carrier density.

Paper Details

Date Published: 3 March 2011
PDF: 6 pages
Proc. SPIE 7939, Gallium Nitride Materials and Devices VI, 79391T (3 March 2011); doi: 10.1117/12.874151
Show Author Affiliations
Ming-Hua Lo, National Chiao Tung Univ. (Taiwan)
Academia Sinica (Taiwan)
Yuh-Jen Cheng, National Chiao Tung Univ. (Taiwan)
Academia Sinica (Taiwan)
Hao-Chung Kuo, National Chiao Tung Univ. (Taiwan)
Shing-Chung Wang, National Chiao Tung Univ. (Taiwan)

Published in SPIE Proceedings Vol. 7939:
Gallium Nitride Materials and Devices VI
Jen-Inn Chyi; Yasushi Nanishi; Hadis Morkoç; Joachim Piprek; Euijoon Yoon, Editor(s)

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