Abstract
Strong localization effect in self-assembled InGaN quantum dots (QDs) grown by metalorganic chemical vapor deposition has been evidenced by temperature-dependent photoluminescence (PL) at different excitation power. The integrated emission intensity increases gradually in the range from 30 to 160 K and then decreases with a further increase in temperature at high excitation intensity, while this phenomenon disappeared at low excitation intensity. Under high excitation, about 40% emission enhancement at 160 K compared to that at low temperature, as well as a higher internal quantum efficiency (IQE) of 41.1%, was observed. A strong localization model is proposed to describe the possible processes of carrier transport, relaxation, and recombination. Using this model, the evolution of excitation-power-dependent emission intensity, shift of peak energy, and linewidth variation with elevating temperature is well explained. Finally, two-component decays of time-resolved PL (TRPL) with various excitation intensities are observed and analyzed with the biexponential model, which enables us to further understand the carrier relaxation dynamics in the InGaN QDs.
Highlights
Ш-nitride-based wurtzite semiconductors InN, GaN, AlN, and their alloys have attracted considerable attention in recent years due to their promising applications in solid state lighting, high-density optical storage, and full-color display [1,2,3]
The developments of the crystal growth technology have led to the commercialization of dazzling blue and green InGaN quantum well (QW) lightemitting-diodes (LEDs) and laser diodes (LDs), the so called “green gap” that the internal quantum efficiency (IQE) of InGaN Quantum well (QW) drops significantly when going to green and longer wavelength regions is still a devilish problem to solve, which is ascribed to 1) increased
Strong localization effect in self-assembled InGaN quantum dots (QDs) is evidenced by temperature (T)-dependent photoluminescence (PL) under different excitation power (P)
Summary
Ш-nitride-based wurtzite semiconductors InN, GaN, AlN, and their alloys have attracted considerable attention in recent years due to their promising applications in solid state lighting, high-density optical storage, and full-color display [1,2,3]. In the last 2 decades, growth techniques of InGaN QDs, i.e., metalorganic chemical vapor deposition (MOCVD) and molecular-beam epitaxy (MBE), are extensively studied and well developed. By using these methods, InGaN QD LEDs and LDs, which emit from. In the InGaN QDs, since the higher indium content, the localized luminescence centers must be much more deeper than that in QWs, which influences the carrier transport, relaxation, and recombination processes in the QDs. In this letter, strong localization effect in self-assembled InGaN QDs is evidenced by temperature (T)-dependent photoluminescence (PL) under different excitation power (P). Time-resolved PL (TRPL) measurements are performed to further understand the carrier relaxation dynamics in the InGaN QDs
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