Optical properties of self-assembled InGaN/GaN quantum dots

Optical spectroscopy under varying temperature is used to investigate sampl es containing planes of self-assembled Ga1-xInxN quantum dots (0.15 < x < 0 .20), embedded in a GaN matrix. The samples have been grown by molecular be am epitaxy on sapphire substrates and the nano-islands have been obtained b y the Stranski-Krastanov growth mode transition. Half-widths at half maximu m as small as 0.05 eV are obtained for photoluminescence (PL) lines at T = 2 K. Increasing the growth time decreases the PL energy and drastically inc reases the PL decay time, as a result of the increasing of the average dot height. Time-resolved PL measurements with variable temperature allow us to observe the competitive influence of several mechanisms, namely the usual radiative and nonradiative recombination processes, plus the carrier feedin g from random fluctuations, which plays a crucial role in the case of the l arger dots. (C) 2001 Elsevier Science B.V. All rights reserved.