Origin of broad luminescence from site-controlled InGaN nanodots fabricated by selective-area epitaxy (Phys. Status Solidi A 3∕2014)

• Published in: Physica status solidi. A, Applications and materials science Vol. 211; no. 3; pp. np - n/a
• Main Authors: Lee, L. K., Aagesen, L. K., Thornton, K., Ku, P.-C.
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 01.03.2014; Wiley Subscription Services, Inc
• Subjects: Computer simulation; Electronics; Epitaxy; Gallium nitrides; Indium gallium nitrides; Morphology; Nanostructure; Quantum dots
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.201470216

GaN/InGaN nanostructures have numerous potential electronic and opto‐electronic applications, such as energy‐selective contacts for hot carrier solar cells and light‐emitting diodes. A joint experimental and computational approach has been developed to understand the properties of GaN/InGaN nanostructures grown by selective area epitaxy (see the article by P.‐C. Ku and co‐workers, pp. 531–535). GaN quantum dots were grown by metal‐organic chemical vapor deposition on a GaN substrate, with a SiO2 mask patterned by electron‐beam lithography used to control the initial quantum dot size and position. The morphology of the quantum dot in the early stages of deposition is non‐uniform, resembling a volcano that gradually fills in and finally takes the shape of a hexagonal pyramid (inset, right). To understand the evolution of the morphology, a phase‐field model was developed to simulate the growth process (inset, left), which included crystallographic orientation‐dependent GaN growth and surface diffusion. Good agreement between simulation and experiment was obtained throughout the growth process. The growth of InGaN layers embedded in the quantum dots was also simulated, and the results were used to explain why the measured photoluminescence spectrum was considerably broader than expected.