Quantum dot origin of luminescence in InGaN-GaN structures

Abstract

We report on resonant photoluminescence ͑PL͒ of InGaN inclusions in a GaN matrix. The structures were grown on sapphire substrates using metal-organic chemical vapor deposition. Nonresonant pulsed excitation results in a broad PL peak, while resonant excitation into the nonresonant PL intensity maximum results in an evolution of a sharp resonant PL peak, having a spectral shape defined by the excitation laser pulse and a radiative decay time close to that revealed for PL under nonresonant excitation. Observation of a resonantly excited narrow PL line gives clear proof of the quantum dot nature of luminescence in InGaN-GaN samples. PL decay demonstrates strongly nonexponential behavior evidencing coexistence of quantum dots having similar ground-state transition energy, but very different electron-hole wave-function overlap.

Quantum dot emission from site-controlled InGaN∕GaN micropyramid arrays

“…4(b). The PL decay trace from the side QW is nonexponential, in agreement with previous measurements, 12 and exhibits a fast initial decay followed by a slower component. The trace from the QD closely matches that observed from the side well in both shape and lifetime.…”

Optical Properties of III–V Quantum Dots

“…In order to confirm our presumption regarding the QD nature of the InGaN/GaN structures on Si, we performed resonant TR PL investigations in a manner similar to that reported for InGaN/GaN multilayers on sapphire [16]. As mentioned above, the continuous function of density of states of QWs leads to fast carrier relaxation into states of minimal energy after resonant excitation significantly above the PL onset.…”

Improving p-type doping efficiency in Al0.83Ga0.17N alloy substituted by nanoscale (AlN)5/(GaN)1 superlattice with MgGa-ON δ-codoping: Role of O-atom in GaN monolayer

“…6,[20][21][22][23][24][25] It has been found that the internal quantum efficiency can be enhanced by nanoscale islands or quantum dots observed in AlGaN. 6,20,24 Moreover, atomic-scale compositional superlattice (SL) has also been observed in Al-rich AlGaN thin films grown by molecular-beam epitaxy.…”