GaN-based vertical-cavity surface emitting laser with 3 λ cavity and hybrid mirrors, consisting of the 25 pairs AlN∕GaN dielectric Bragg reflector and the 8 pairs Ta2O5∕SiO2, was fabricated. The laser action was achieved under the optical pumping at room temperature with a threshold pumping energy density of about 53mJ∕cm2. The laser emits 448 nm blue wavelength with a linewidth of 0.25 nm and the laser beam has a degree of polarization of about 84%.

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We successfully fabricated nitride-based light-emitting diodes (LEDs) with 22 undercut sidewalls. The 22 etching undercut sidewalls were achieved by controllable inductively coupled plasma reactive ion etching. With a 20-mA current injection, the output powers of the LED with 22 undercut sidewalls and standard LED were 5.1 and 3 mW, respectively-a factor of 1.7 times enhancement. It was found that such undercut sidewalls could enhance the probability of escaping the photons outside from the LED in the near horizontal and in-plane directions. This simple and controllable method is beneficial to fabricate brighter LEDs.Index Terms-Etching profile, GaN, light-emitting diode (LED), light extraction efficiency.

In this paper, we report a GaN-based microcavity light-emitting diode (MCLED) which is composed of 25 pairs of high-reflectivity GaN/AlN distributed Bragg reflector (DBR) and 6 pairs of ex-situ deposited SiO2/TiO2 dielectric mirrors. The electroluminescence peak of this structure matched well with the high reflectance area of the top and bottom DBRs, and shows a narrow emission of approximately 6.7 nm. The fabricated device also shows a more excellent performance on the stability of the emission peak wavelength while varying injection current density and operating temperature than a regular LED.

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