“Advances Stimulated emission from semi-polar (11-22) GaN overgrown on sapphire”
B. Xu, L. Jiu, Y. Gong, Y. Zhang, L. C. Wang, J. Bai, and T. Wang
AIP Advances 7, 045009 (2017); doi: http://dx.doi.org/10.1063/1.4981137

Abstract

(11-22) semi-polar GaN is expected to exhibit major advantages compared with current c-plane polar GaN in the fabrication of long wavelength such as green and yellow emitters. However, all the III-nitride based semi-/non- polar laser diodes (LDs) reported so far have been achieved exclusively based on homo-epitaxial growth on extremely expensive free-standing GaN substrates with a very limited size. In this paper, we have observed a stimulated emission at room temperature achieved on our semi-polar (11-22) GaN overgrown on a micro-rod arrayed template with an optimized design on m-plane sapphire. This has never been achieved previously on any semi-polar GaN grown on sapphire. Furthermore, an optical gain of 130cm−1 has been measured by means of performing a standard laser stripe-length dependent optical measurement. The values of the threshold and the optical gain obtained are comparable to those of the c-plane GaN reported so far, further validating the satisfactory crystal quality of our overgrown semi-polar (11-22) GaN on sapphire. This represents a major step towards the development of III-nitride semi-polar based LDs on sapphire, especially in the long wavelength regime.

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1-4981137-figures-online-f1
(a) Emission spectra of the semi-polar overgrown GaN measured as a function of an optical pumping density from 130 to 1100 kW/cm2; (b) Integrated intensity and line-width of the stimulated emission as a function of an optical pumping density. Inset of (b): Integrated intensity of a stimulated emission as a function of an optical pumping density measured on a standard c-plane GaN sample grown on sapphire for comparison.

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New AIP Advances paper represents a major step towards the development of III-nitride semi-polar based LDs on sapphire