Jin-Joo Song’s research while affiliated with Oklahoma State University and other places

Published by SPIE The papers included in this volume were part of the technical conference cited on the cover and title page. Papers were selected and subject to review by the editors and conference program committee. Some conference presentations may not be available for publication. The papers published in these proceedings reflect the work and thoughts of the authors and are published herein as submitted. The publisher is not responsible for the validity of the information or for any outcomes resulting from reliance thereon.

We report a comprehensive study on the optical properties of GaN- and AlGaN-based lasing structures at high-levels of optical excitation (carrier densities of 1017-1020 cm-3) and identify critical issues necessary for the development of near- and deep-UV light emitting devices. We successfully achieved room temperature stimulated emission (SE) with emission wavelengths ranging from 351 nm to 373 nm in a variety of samples. Through an analysis of the temperature-dependent lasing characteristics, combined with absorption and time-resolved photoluminescence measurements, we estimated the carrier density required to achieve the SE threshold in GaN epilayers. We found that in AlGaN epilayers, the onset of SE (∼1019 cm-3) occurs at carrier densities one order of magnitude higher than in thick GaN epilayers, indicating that an electron-hole plasma is the dominant gain mechanism over the entire temperature range studied (10 K to 300 K). A remarkably low lasing threshold was observed in GaN/AlGaN heterostructures over the temperature range of 10 K to 300 K. Our experimental results indicate that GaN/AlGaN heterostructures could be used to efficiently generate laser emission with wavelengths shorter than 373 nm. The implications of this study on the development of UV laser diodes is discussed.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

This chapter explains many issues related to gain mechanisms, pump-probe experiments, microstructure lasing, imaging, and high-temperature optical properties of the material system, as well as provides some background information on the general properties of III-nitride thin films. The capacity of optical storage is limited by the spot size of the laser beam. The minimum spot size to which a laser can be focused is proportional to the wavelength of the laser light. Because of the shorter emission wavelength of lasers based on GaN thin films, storage and high-resolution printing are natural choices for GaN-laser-diode (LD) applications. To lower production costs, shorter wavelength and higher power LDs are necessary. There are some limitations, however, as to how short the wavelength needs to be. The organic photoreceptors used in printers should be sensitive to the laser wavelengths, and expensive optics should not be used. At low temperatures, near-band-edge luminescence spectra observed from most GaN samples are dominated by strong, sharp emission lines that result from the radiative recombination of free and bound excitons.