We report on low temperature photoluminescence studies of ZnO nanowires embedded in different polymers. Comparing the spectra as-grown and nanowires, we find a decrease deep-level emission an increase near band-edge after embedding process. The is dominated by surface exciton band. observed effects are independent selected polymer. scales with balling abilities propose model to explain spectral changes.

We report on systematic investigations of the dynamics surface-excitonic (SX) near-band-edge photoluminescence ZnO nanowires observed at $\ensuremath{\approx}3.365\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. The temporal evolution SX emission vapor-phase grown with diameters $d=40--130\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ is studied as a function spectral position, temperature, and excitation intensity. A phenomenological rate-equation model developed discussed which able to describe...

In the present paper, studies on state of strain in single and ensembles nanocolumns investigated by photoluminescence spectroscopy will be presented. The GaN were either grown a bottom-up approach or prepared top-down etching compact layers Si(111) sapphire (0001) substrates. Experimental evidence for relaxation was found. difference development value different could verified spatially resolved micro-photoluminescence separated from their substrate. A common D0X spectral position at 3.473...

InGaN quantum dots were grown by metal-organic vapor phase epitaxy using a phase-separation process based on spinodal and binodal decomposition. Uncapped structures which show phases with two different In contents the surface. The high-In-content accumulates to huge islands while low-In content forms flat meander quantum-dot-like dissolution of high-In-containing is very sensitive growth temperature GaN capping there no significant change dot structures. samples investigated transmission...

We investigate both experimentally and theoretically the excitonic absorption in ZnSe a temperature range between 2 60 K with increasing densities of carriers. For higher temperatures weak redshift exciton resonance is found which turns into blueshift for lower temperatures. While widely used simplified treatment scattering processes within static screening approximation fails completely to describe this thermally induced crossover, it can be explained by interplay Coulomb-Hartree-Fock...

We investigated the photoluminescence properties of ZnO nanowires coated with Au, Ag, and Pt nanoparticles deposited by dc sputtering. A strong enhancement near-band-edge emission was observed in all metal-coated samples but also if were treated Ar plasma without any nanoparticle deposition. High-resolution spectroscopy revealed hydrogen-donor-bound-exciton indicating unintentional hydrogen incorporation. shorter decay time cases. The results indicate that incorporation plays a dominant role...

Four-wave-mixing signals from excitons under linear-circular polarized excitation exhibit an elliptical polarization, depending on both the pulse delay and spectral position. Besides resonances corresponding to exciton-biexciton transitions, a breakup of exciton line is found reflecting influence correlations four-point level. An analysis accounting for density, bound biexciton, exciton-exciton scattering continuum reveals that these features are not due antibound two-exciton state. Instead,...

The optical properties of ZnO nanorods realized by an advanced low-temperature aqueous chemical growth on both silicon and plastic substrates are presented. Systematic photoluminescence investigations in the temperature range 4–293K reveal strong well-resolved near-band-edge emission even for rods substrate, a weak deep-level emission. At intermediate temperatures phonon replicas excitonic lines observable. optimum molar concentration solution obtaining good quality is shown to lie between...

Abstract We present evidence for the existence of a hybrid state Tamm plasmons and microcavity exciton polaritons in II-VI material based sample covered with an Ag metal layer. The bare cavity mode shows characteristic anticrossing Tamm-plasmon mode, when microreflectivity measurements are performed different detunings between plasmon mode. When is resonance polariton four eigenstates observed due to coupling cavity-photon heavy- light-hole excitons. If tuned, these resonances will exhibit...

Monolithic II-VI pillar microcavities made of ZnSSe and MgS∕ZnCdSe supperlattices have been fabricated by molecular-beam epitaxy focused-ion-beam etching. Discrete optical modes the are studied in photoluminescence measurements. The identified means calculations based on an extended transfer matrix method. Achievable Purcell factors well above 10 can be estimated from measured quality calculated mode volumes.

The influence of ZnO seed crystals and postgrowth annealing on low-temperature aqueous chemically grown nanorods is analyzed. At the crystal/nanorod interface a high density structural defects leads to emission at 3.332 eV, attributed excitons bound defects. This peak absent for crystals, very pronounced rods shorter lengths reduced longer nanorods. After in oxygen nitrogen atmosphere, near-band-edge excitonic transitions sharpen deep-level strongly reduced. Time-resolved photoluminescence...

We present electrically driven luminescence from single InGaN quantum dots embedded into a light emitting diode structure grown by metal-organic vapor-phase epitaxy. Single sharp emission lines in the green spectral region can be identified. Temperature dependent measurements demonstrate thermal stability of dot up to 150 K. These results are an important step towards applications like single-photon emitters, which basis for incorporating plastic optical fibers as well modern concepts free...

Abstract Second‐harmonic generation and two‐photon induced photoluminescence from arrays of ZnO nanowires single under excitation with femtosecond pulses is experimentally studied. The ratio relevant components the nonlinear χ (2) tensor obtained. nanowire array laser induces significant heating free‐standing nanowires. heat distribution analyzed in phenomenological finite‐element studies. Two‐photon a broad internal used to perform single‐nanowire transmission experiment. From transmitted...

We analyze the near-band-edge photoluminescence of electrochemically deposited ZnO nanowires and directly correlate properties with carrier concentration in as determined from electrochemical impedance spectroscopy. find a donor density 8×1019 cm−3 as-deposited show that emission results band-to-band recombination processes (delocalized states). A band centered at 3.328 eV scales diameter is assigned to involving surface states. annealing 500 °C air reduces by more than one order magnitude,...

Self-organized and highly ordered GaN nanorods were grown without catalyst on r-plane sapphire using a combination of molecular beam epitaxy metal–organic vapor-phase epitaxy. AlN nucleation centers for the prepared by nitridation in reactor, while A coalesced two-dimensional layer was observed between nanorods. The are inclined 62° towards -directions a-plane layer. high degree ordering structural perfection confirmed micro-photoluminescence measurements.

The use of ZnO bulk and especially nanolayer nanowire structures for novel device applications has led to a renewal interest in high-electron-density processes ZnO, such as those occurring during lasing ZnO. Using pump-probe reflectometry technique, we investigate the ultrafast exciton dynamics under femtosecond laser excitation close conditions. Under intense by 266-nm (fs) pump pulses, resonance becomes highly damped does not recover several picoseconds. This slow recovery indicates...

Laser-thinning of 2D materials such as MoS2 is a promising approach for local reduction the number multilayers down to monolayer. For precise control thinning process real-time monitoring required. In this work, short-wavelength lasers emitting at 325 or 406 nm respectively are used laser-thinning and simultaneous Raman photoluminescence spectroscopy MoS2. The time evolution bands during shows layer-by-layer transformation into amorphous MoOx in an oxygen-containing atmosphere. addition E2g1...

Excitonic luminescence in ZnO exhibits subnanosecond lifetimes combined with high efficiency, which makes epitaxial a promising ultrafast scintillator material for envisaged imaging applications data rate. thin films on sapphire show external ultraviolet electron-photon conversion efficiencies up to 0.42photons∕(keVe−) at room temperature and only minor lateral microscopic cathodoluminescence intensity variations. Peak shifts occasionally observed double peaks found spectra of dependence the...

By use of an optical coherent-control technique we demonstrate and analyze the control transitions involved in generation four-wave-mixing signals a semiconductor quantum well for two different directions sequences excitation pulses. Results are presented frequency- as time-resolved signals. A doubling coherent switching frequency is found which occurs if laser pulses performing process contribute quadratically to wave-mixing signal. direct comparison between experiment microscopic theory...

We report on the investigation of correlated spectral properties two different surface-related photoluminescence bands in ZnO nanowires. show that position and temperature-dependent intensity emission band A are directly with surface-exciton SX. measure thermal activation energies both present time-resolved data to deduce decay time band. propose a model explain experimental observations assign excitons bound structural defects surface layer