Photoluminescence behavior of quantum dots in spherical glass microcavity

Micrometer-sized spherical glass microspheres were fabricated. CdSeS semiconductor nanometer clusters were incorporated into spherical microcavities. When a single microsphere was excited by a laser beam, the whispering gallery mode resonance of the photoluminescence of CdSeS quantum dots in the spherical microcavities was realized by the multiple total internal reflections at the spherical interface. The coupling of restricted electronic and photonic states was realized.

Photoluminescence study of CdSexS1-x quantum dots in a glass spherical microcavity

The photoluminescence (PL) of CdSexS1-x semiconductor quantum dots (QDs) in a glass spherical microcavity is investigated. The CdSexS1-x semiconductor clusters embedded in a glass matrix are fabricated by using the heat treatment method. Periodical structures consisting of sharp spectral lines are observed in the PL spectra of CdSexS1-x QDs, which can be well explained by the coupling with the whispering gallery modes of the spherical microcavity based on Mie scattering theory.

Exciton energy of the InAs/GaAs self-assembled quantum dot in a semiconductor microcavity

We report on the theoretical study of the interaction of the quantum dot (QD) exciton with the photon waveguide models in a semiconductor microcavity. The InAs/GaAs self-assembled QD exciton energies are calculated in a microcavity. The calculated results reveal that the electromagnetic field reduces the exciton energies in a semiconductor microcavity. The effect of the electromagnetic field decreases as the radius of the QD increases. Our calculated results are useful for designing and fabricating photoelectron devices.

Quantum dots in glass spherical microcavity

Glass spherical microcavities containing CdSexS1-x semiconductor quantum dots (QDs) are fabricated. The coupling between the optical emission of embedded CdSexS1-x QDs and spherical cavity modes is realized. When the luminescence of QDs is excited by a laser beam, the strong whispering gallery mode resonance with high Q factors is achieved in the photoluminescence spectra. (C) 2001 American Institute of Physics.

Radiation of dressed excitons in the semiconductor microcavity

In this paper, we introduced the dressed exciton model of the semiconductor micro-cavity device. In the semiconductor micro cavity of vertical-cavity surface-emission device, the excitons first coupled with the cavity through an intra-electromagnetic field and formed the dressed excitons. Then these dressed excitons decayed into the vacuum cavity optical mode, as a multiparticle process. Through the quantum electrodynamics method, the dipole emission density and system energy decayed equation were obtained. And it was predicted that the excitons decay into a very narrow mode when the exciton-cavity coupling becomes strong enough.

Ge related defect energy and microcavity effect in GaN epitaxial layer

Using solid-phase regrowth technique, Pd/Ge contact has been made on the GaN layer, and very good ohmic behavior was observed for the contact. The Photoluminescence (PL) spectra for different structures formed by the Pd/Ge contact, GaN layer, sapphire substrate, and mirror were studied, and a defect-assisted transition was found at 450 nm related to Ge impurity. The results show that the microcavity effect strongly influences the PL spectra of the band-gap and defect-assisted transitions.

Dynamics of Cavity Polaritons in a GaAs Quantum-well Semiconductor Microcavity

To provide the dynamics of cavity polariton in semiconductor microcavity containing GaAs quantum-well, the dispersions of the three cavity polaritons have been given by the model of three coupled oscillators, meanwhile the linewidths, group velocities and the mass of the three cavity polaritons have been demonstrated. The results indicated that because of the weight occupied by the photon, heavy hole exciton and light hole extiton in the three cavity ploariton the cavity polaritons exhibited different dynamic behaviors.

RADIATION OF DRESSED EXCITONS IN THE SEMICONDUCTOR MICROCAVITY

于2010-11-23批量导入

Eigenmode confinement in semiconductor microcavity lasers with an equilateral triangle resonator

We analyze the mode behaviors for semiconductor lasers with an equilateral triangle resonator by deriving the mode field distribution and the eigenvalue equation. The eigenvalue equation shows that the longitudinal mode wavelength interval is equivalent to that of a Fabry-Perot cavity with the cavity length of 1.5a, where a is the side length of the equilateral triangle resonator. The transverse waveguiding is equivalent to as a strip waveguide with the width of root 3a/ 2, and the number of transverse modes supported by the resonator is limited by the total reflection condition on the sides of the equilateral triangle. Semiconductor microcavity laser with an equilateral triangle resonator is suitable to realize single mode operation, and the mode wavelength can be adjusted by changing the side length.

Cooperative spontaneous emission of excitons in the semiconductor microcavity

We have studied the spontaneous emission of polarized excitons in the GaInP/AlGaInP VCSEL from 30K to room temperature. It is observed that the spontaneous emission peak enters and leaves the resonant regime. At the resonant regime, the emission intensities of the perpendicular and horizontal polarized exciton are enhanced at different ratio to those in non-resonant regime. These experiment results are explained through the dressed exciton theory of the semiconductor microcavity device. From this theory, the intensity enhancement and the polarization dependence are understood as cooperative emission and the microcavity anisotropy.

Lasing of CdSSe quantum dots in glass spherical microcavity

Glass spherical microcavities containing CdSSe semiconductor quantum dots (QDs) of a few microns in diameter are fabricated using a physical method. When a single glass microspherical cavity is excited by a laser beam at room temperature, very strong and sharp whispering gallery modes are shown on the background of PL spectra of CdSSe QDs, which confirms that coupling between the optical emission of embedded QDs and spherical cavity modes is realized. For a glass microsphere only 4.6 mum in diameter, it was found that the energy separation is nearly up to 26 nm both for TE and TM modes. With the increasing excitation intensity, the excitation intensity dependence of the emission intensity is not linear in the double-logarithmic scale. Above the threshold value, the linewidths of resonance modes become narrower. The lasing behavior is achieved at relatively low excitation intensity at room temperature. High optical stability and low threshold value make this optical system promising in visible microlaser applications. (C) 2002 Elsevier Science B.V. All rights reserved.

Realization of high efficiency microcavity top-emitting organic light-emitting diodes with highly saturated colors and negligible angular dependence

An alternative way to optimize the emission characteristics of a microcavity top-emitting organic light-emitting diode (TOLED) based on a simple device structure is demonstrated via combining a comprehensive theoretical analysis in the microcavity effects with the experimental modification in the carrier injection of both electrodes. It can be seen that the resulting TOLED exhibits much higher efficiencies and a more saturated color than those of the corresponding conventional bottom-emitting device, as well as hardly detectable color shift with viewing angles. Such a strategy may be more feasible in practical application for active-matrix organic light-emitting diode displays.

Tunability of resonant wavelength by Fabry-Perot microcavity in organic light-emitting diodes

Distributed Bragg reflectors (DBR) with different reflection wavelengths were designed, and were used to fabricate microcavity organic light-emitting diodes (OLEDs) based on tris(8-hydroxyquinoline)-aluminum (Alq(3)) as the emitter and N, N'-di(naphthalene-1-yl)-N, N'-diphenyl-benzidine (NPB) as the hole-transporting layer. The microcavity was composed of DBR dielectric mirror and metal electrode aluminum (Al) mirror. Some effects of vertical optical Fabry-Perot microcavity on spontaneous emission in OLEDs were investigated. Spectral narrowing, enhancement of emitting intensity and anglular dependence of emission were observed due to the microcavity effect. It was found experimentally that the utilization of DBR is a better method to adjust the emissive mode in the resonant cavity in OLEDs well. Thus the realization of different color light emission becomes possible by the combination of carefully designed microcavity and electroluminescent organic semiconductors in a single LED.

Microcavity effects on emissive color and electroluminescent performance in organic light-emitting diodes

Microcavity organic light-emitting diodes having a top metal mirror and a bottom dielectric mirror, which was distributed Bragg reflectors (DBR) fabricated by using TiO2-SiO2 alternative dielectric multilayer with a central stop-band and two sub-stop-bands, were fabricated. In the devices, the active layers consisted of a hole-transporting layer N,N'-di(naphthalene-1-yl)-N,N'-diphenylbenzidine (NPB) and an electron- transporting/emitting layer tris(8-hydroxy-quinoline) aluminum (Alq(3)). The relationship of the electroluminescent (EL) spectrum and efficiency with the thickness of the active layer and metal layer was studied. It was found that the EL emissive color did not strongly depend on the thickness of the organic layer and metal layer, which was attributed to the excellent photon confinement role of the narrow stop-band of the used dielectric mirror. Thus, high efficiency microcavity organic light-emitting diodes were achieved, and the peak wavelength and color purity were not obviously changed, via optimizing the thickness of organic layer and metal electrode.