Abstract Remote epitaxy via graphene has recently attracted significant attention, since it provides the possibility to lift-off grown epitaxial layer, reuse substrate, and produce flexible devices. However, extensive research is still necessary fully understand III-nitride formation on van der Waals surface of a two-dimensional material utilize remote its full potential. In this work, growth GaN epilayer using GaN/sapphire template covered with monolayer presented. Metalorganic vapor phase...

The emission efficiency droop and internal quantum (IQE) in AlGaN epilayers heterostructures were investigated by studying photoluminescence intensity dependence on excitation power density at different temperatures the range from 8 to 300 K three samples with similar Al content (33%-35%) strength of carrier localization: an epilayer multiple wells well widths 5.0 2.5 nm. It is shown that phenomena leading strongly influence temperature and, therefore, affect estimation IQE based this...

Photoluminescence studies of carrier dynamics in AlGaN epilayers with different degrees localization and densities nonradiative recombination centers show that the prevailing droop mechanism strong comparatively high density is enhanced due to delocalization at elevated density. The photoluminescence was investigated under quasi-steady-state excitation temperature range from 8 300 K. results proved onset this effect below threshold for high-density effects epilayers, such as heating, phase...

<title>Abstract</title> To improve the emission efficiency of InGaN/GaN multiple quantum wells (MQWs), we used high indium content short-period superlattice (SPSL) underlayer and validated approach by studying structural optical properties. The SPSL underlayers were deposited at temperatures equal to or below growth temperature active region MQWs. impact such was studied using XRD, photoluminescence (PL), light-induced transient grating (LITG) techniques. large redshift PL band higher low...

Time-resolved photoluminescence and light-induced transient grating measurements of GaN epilayers show that the decay can be described by two coupled exponential terms carrier mobility lifetime in are correlated within model which accounts for nonradiative recombination predominantly at dislocations. The obtained results demonstrate migration-enhanced metalorganic chemical vapor deposition (MEMOCVD™) allows growth high-quality on sapphire substrates with dislocation density close to 108cm−2,...

The trench defects in InGaN/GaN multiple quantum well structures are studied using confocal photoluminescence (PL) spectroscopy and atomic force microscopy. A strong blueshift (up to ∼280 meV) an intensity increase (by up a factor of 700) the emission demonstrated for regions enclosed by loops. influence difference width inside outside loops observed transmission electron microscopy, compositional pulling effect, strain relaxation loop, corresponding reduction built-in field on PL band peak...

Excitation-power dynamics of near-band-edge photoluminescence (PL) peak position in InxGa1−xN∕GaN multiple quantum wells (x∼0.15) was analyzed as a function well width. The analysis based on energy reference provided by photoreflectance (PR) spectra. difference spectral the PR feature and low-excitation PL band (the Stokes Shift) revealed carrier localization energy, which exhibited remarkable sensitivity to width, increasing from 75meV 2nm about 250meV 4nm wells. Meanwhile collating data...

A set of Al0.35Ga0.65N∕Al0.49Ga0.51N multiple quantum wells (MQWs) with fixed barrier width and well widths varying from 1.65to5.0nm has been grown by metal-organic chemical vapor deposition. Carrier dynamics in the MQWs were studied using time-resolved photoluminescence (PL) spectroscopy light-induced transient grating (four wave mixing) technique. The authors observed that lifetime nonequilibrium carriers (excitons) increases decreasing interpreted effect stronger localization preventing...

Stimulated emission (SE) is studied in AlGaN/AlGaN multiple quantum wells (MQWs) with different Al content grown on sapphire substrate. The spectra of spontaneous and stimulated their transformations increasing temperature as well thresholds were measured the range from 8 to 300 K. Phonon-assisted band broadening low-Al-content MQWs double-scaled potential profile high-Al-content observed samples linked carrier localization conditions. dependence threshold was similar where transitions occur...

The influence of carrier localization on photoluminescence efficiency droop and stimulated emission is studied in AlGaN multiple quantum wells with different strength localization. We observe that delocalization at low temperatures predominantly enhances the nonradiative recombination causes droop, while main effect elevated enhancement PL due to increasing contribution bimolecular free carriers. When thermal energy exceeds dispersion potential fluctuations causing localization, caused by...

Growth of BGaN epitaxial layers by metalorganic chemical vapor deposition (MOCVD) using triethylboron (TEB) as a boron source was studied on 6H-SiC substrate and GaN AlN templates sapphire. X-ray diffraction, atomic force microscopy photoluminescence spectroscopy were exploited to characterize the structural quality, surface morphology, luminescence efficiency, content. Silicon carbide shown be slightly superior AlN/sapphire considerably better than GaN/sapphire most favorable incorporate...

Dynamics of radiative and nonradiative recombination non-equilibrium carriers is investigated in thick AlGaN epitaxial layers with Al content ranging from 0.11 to 0.71. The internal quantum efficiency (IQE) the epilayers was obtained using two approaches: either estimated PL measurements or calculated coefficients a simple ABC model, retrieved by fitting kinetics light induced transient gratings (LITG). At photoexcited carrier densities below ~1019 cm−3, both approaches provided similar IQE...

The remote epitaxy of GaN epilayers on GaN/sapphire templates was studied by using different graphene interlayer types. Monolayer, bilayer, double-stack monolayer, and triple-stack monolayer graphenes were transferred onto a wet transfer technique. quality the interlayers examined Raman spectroscopy. impact type nucleation analyzed scanning electron microscopy. interface structural transmission microscopy X-ray diffraction, respectively. influence is discussed in terms differences between...

Monte Carlo simulation of phonon-assisted localized exciton hopping has been employed to describe the photoluminescence linewidth variation with temperature and reveal band potential profile ternary AlGaN epilayers different carrier lifetimes. The lifetimes 30 190 ps were experimentally determined in layers AlN buffers grown by conventional metal-organic chemical vapor deposition (MOCVD) migration-enhanced MOCVD (MEMOCVD™), respectively. is shown consist double-scaled fluctuations. Exciton...

The effect of carrier localization on stimulated emission (SE) in Al0.35Ga0.65N/Al0.49Ga0.51N quantum wells (QWs) sapphire substrate was studied under photoexcitation the edge configuration temperature range from 8 K to 300 K. band potential profile responsible for modulated by variation QW width and monitored using fitting experimental dependence spontaneous luminescence that obtained Monte Carlo simulation exciton hopping. A faster increase SE threshold with increasing observed narrow QWs...

BGaN epilayers were grown on GaN/sapphire templates in hydrogen atmosphere by metal organic chemical vapor deposition (MOCVD). The growth was attempted at different temperatures and flow rates of triethylboron, which used as boron precursor. According to XRD measurements, up 2.9% incorporated 500 nm-thick layers deposited 870 °C. Comparison results with the red shift observed photoluminescence band increasing content confirms an extremely large value ∼10 eV for bowing parameter BGaN.

We report on using Migration Enhanced Metal Organic Chemical Vapor Deposition (MEMOCVDTM) buffers for increasing lifetime of non-equilibrium carriers in GaN and AlGaN players grown sapphire SiC substrates. Photoluminescence (PL) the light-induced grating technique (LITG) were used comparative study epilayers with MEMOCVDTM multilayered conventional buffers. Measurements layers show carrier more than 300 ps respectively MEMOCVD buffer which is 4 times higher compared to MOCVD In layers, PL...

Luminescence efficiency droop has been studied in AlGaN epitaxial layers and multiple quantum wells (MQWs) with different strength of carrier localization a wide range temperatures. It is shown that the dominant mechanism leading to droop, i.e., reduction at high densities, determined by thermalization conditions ratio between thermal energy depth. The mechanisms, such as occupation-enhanced redistribution nonthermalized carriers, enhancement nonradiative recombination due delocalization,...

Abstract AlGaN epilayers with different aluminum molar fractions have been comparatively studied by photoluminescence (PL) and light‐induced transient grating (LITG) techniques. The carrier diffusion length determined LITG is shown to be close the average distance between two first‐neighbor dislocations, which was roughly estimated using dislocation density obtained etch pit technique. For containing same amount of Al, lifetime PL intensity are inversely proportional limit serving as...

Abstract Excitation power density dependence of photoluminescence (PL) efficiency is studied in the temperature range from 8 to 300 K for AlGaN multiple quantum well structures containing wells different width. PL droop observed and effect on width lattice discussed. Photoluminescence band shape reveals strong carrier heating. It shown that heating has a substantial influence droop, especially at low temperatures. Fitting with obtained by Monte Carlo simulation (exciton) hopping via...