InGaN/GaN Quantum Dots on Silicon With Coalesced Nanowire Buffer Layers: A Potential Technology for Visible Silicon Photonics

We have investigated the structural and optical characteristics of planar GaN epitaxial layers on silicon substrates, formed by coalescing an array of GaN nanowires, and of In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.32</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.68</sub> N/GaN self-organized quantum dots grown on the GaN layer. The as-grown coalesced GaN layer is of the cubic crystalline form, with a large density of stacking faults, that transforms to the wurtzite form, devoid of most of the stacking faults, upon post-growth annealing. Multiple layers of the quantum dots emit at 550 nm. Temperature-dependent and time-resolved photoluminescence measurements have been made to determine the temperature dependent radiative and non-radiative lifetimes of the quantum dots.

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