Real-time observation of delayed excited-state dynamics in InGaN/GaN quantum-wells by femtosecond transient absorption spectroscopy.

This work employs femtosecond transient absorption spectroscopy to investigate the ultrafast carrier dynamics of bound states in InGaN/GaN quantum wells. The ground state (GS) dynamics usually dominate these characteristics, appearing as a prominent peak in the absorption spectra. It is observed that the excited state also contributes to the overall dynamics, with its signature showing up later.

Reduced Auger Coefficient through Efficient Carrier Capture and Improved Radiative Efficiency from the Broadband Optical Cavity: A Mechanism for Potential Droop Mitigation in InGaN/GaN LEDs.

Efficiency droop at high carrier-injection regimes is a matter of concern in InGaN/GaN quantum-confined heterostructure-based light-emitting diodes (LEDs). Processes such as Shockley-Reed-Hall and Auger recombinations, electron-hole wavefunction separation from polarization charges, carrier leakage, and current crowding are identified as the primary contributors to efficiency droop. Auger recombination is a critical contributor owing to its cubic dependence on carrier density, which can not be circumvented using an advanced physical layout.

Gradual Carrier Filling Effect in "Green" InGaN/GaN Quantum Dots: Femtosecond Carrier Kinetics with Sequential Two-Photon Absorption.

Quantum dots (QDs) allow for a significant amount of strain relaxation, which is helpful in GaN systems where a large lattice mismatch needs to be accommodated. InGaN QDs with a large indium composition are intensively investigated for light emitters requiring longer wavelengths. These are especially important for developing high-efficiency white light sources.

Theoretical modelling of exciton binding energy, steady-state and transient optical response of GaN/InGaN/GaN and AlGaN/GaN/AlGaN core-shell nanostructures.

Here, we present an efficient 1D model to describe carrier confinement in GaN/InGaN/GaN and AlGaN/GaN/AlGaN core-shell nanostructures (CSNs) within the effective mass framework. A self-consistent procedure combined with hydrogenic model is implemented to estimate exciton binding energy in these CSNs, as a function of CSN dimensions, polarization charge and alloy composition. A 3-fold higher exciton binding energy in these CSNs than that in planar counterparts is attributed to an increased electron-hole overlap.

Enhanced luminescence from InGaN/GaN nano-disk in a wire array caused by surface potential modulation during wet treatment.

Here we have demonstrated the profound impact of surface potential on the luminescence of an array of InGaN/GaN nano-disk in a wire heterostructure. The change in surface potential is brought about by a combination of dry and successive wet-processing treatments. The photoluminescence (PL) properties are determined as a function of size and height of this array of nano-disks.

Determination of strain relaxation in InGaN/GaN nanowalls from quantum confinement and exciton binding energy dependent photoluminescence peak.

GaN based nanostructures are being increasingly used to improve the performance of various devices including light emitting diodes and lasers. It is important to determine the strain relaxation in these structures for device design and better prediction of device characteristics and performance. We have determined the strain relaxation in InGaN/GaN nanowalls from quantum confinement and exciton binding energy dependent photoluminescence peak.