Polar and semipolar GaN/Al0.5Ga0.5N nanostructures for UV light emitters

• Published in: Semiconductor science and technology Vol. 29; no. 8
• Main Authors: Brault, J, Rosales, D, Damilano, B, Leroux, M, Courville, A, Korytov, M, Chenot, S, Vennéguès, P, Vinter, B, De Mierry, P, Kahouli, A, Massies, J, Bretagnon, T, Gil, B
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.08.2014
• Subjects: Condensed Matter; light emitting diodes; molecular beam epitaxy; Other; Physics; quantum dots; self-assembled nanostructures; time resolved photoluminescence; nitrides UV LEDs
• ISSN: 0268-1242; 1361-6641
• DOI: 10.1088/0268-1242/29/8/084001

AlxGa1−xN-based ultra-violet (UV) light emitting diodes (LEDs) are seen as the best solution for the replacement of traditional mercury lamp technology. By adjusting the Al concentration, a large emission spectrum range from 360 nm (GaN) down to 200 nm (AlN) can be covered. Owing to the large density of defects typically present in AlxGa1−xN materials usually grown on sapphire substrates, LED efficiencies still need to be improved. Taking advantage of the 3D carrier confinement, quantum dots (QDs) are among the solutions currently under investigation to improve the performances of UV LEDs. The objectives of this work are to present and discuss the morphological and optical properties of GaN nanostructures grown by molecular beam epitaxy on the (0 0 0 1) and the (11-22) orientations of Al0.5Ga0.5N. In particular, the dependence of the morphological properties of the nanostructures on the growth conditions and the surface orientation will be presented. The optical characteristics as a function of the nanostructure design (size, shape and dimensionality) will also be shown and discussed. The electroluminescence characteristics of a first series of QD-based GaN Al0.5Ga0.5N LEDs grown on the polar (0 0 0 1) plane will be investigated.