Fabrication and lasing characteristics of GaN nanopillars

Ming-Hua Lo; Yuh-Jen Cheng; Hao-Chung Kuo; Shing-Chung Wang

doi:10.1117/12.874151

3 March 2011 Fabrication and lasing characteristics of GaN nanopillars

Ming-Hua Lo, Yuh-Jen Cheng, Hao-Chung Kuo, Shing-Chung Wang

Proceedings Volume 7939, Gallium Nitride Materials and Devices VI; 79391T (2011) https://doi.org/10.1117/12.874151
Event: SPIE OPTO, 2011, San Francisco, California, United States

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.

Citation Download Citation

Ming-Hua Lo, Yuh-Jen Cheng, Hao-Chung Kuo, and Shing-Chung Wang "Fabrication and lasing characteristics of GaN nanopillars", Proc. SPIE 7939, Gallium Nitride Materials and Devices VI, 79391T (3 March 2011); https://doi.org/10.1117/12.874151

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