Nanoscale-cavity enhancement of color conversion with colloidal quantum dots embedded in the surface nano-holes of a blue-emitting light-emitting diode.

Although the method of inserting colloidal quantum dots (QDs) into deep nano-holes fabricated on the top surface of a light-emitting diode (LED) has been widely used for producing effective Förster resonance energy transfer (FRET) from the LED quantum wells (QWs) into the QDs to enhance the color conversion efficiency, an important mechanism for enhancing energy transfer in such an LED structure was overlooked. This mechanism, namely, the nanoscale-cavity effect, represents a near-field Purcell effect and plays a crucially important role in enhancing the color conversion efficiency. Here, we demonstrate the results of LED performance, time-resolved photoluminescence (TRPL), and numerical simulation to elucidate the nanoscale-cavity effect on color conversion by inserting a photoresist solution of red-emitting QDs into the nano-holes fabricated on a blue-emitting QW LED.

Enhancement of the Modulation Response of Quantum-Dot-Based Down-Converted Light through Surface Plasmon Coupling.

In this paper, we first elaborate on the effects of surface plasmon (SP) coupling on the modulation responses of the emission of a light-emitting diode (LED) and its down-converted lights through colloidal quantum dots (QDs). The results of our past efforts for this subject are briefly discussed. The discussions lay the foundation for the presentation of the new experimental data of such down-converted lights in this paper.

Further emission efficiency improvement of a commercial-quality light-emitting diode through surface plasmon coupling.

It is usually believed that surface plasmon (SP) coupling is practically useful only for improving the performance of a light-emitting diode (LED) with a low intrinsic internal quantum efficiency (IQE). In this Letter, we demonstrate that the performance of a commercial-quality blue LED with a high IQE (>80%) can still be significantly improved through SP coupling based on a surface Ag nanoparticle (NP) structure. The performance improvement of such an LED is achieved by increasing the Mg doping concentration in its p-AlGaN electron blocking layer to enhance the hole injection efficiency such that the p-GaN layer thickness can be significantly reduced without sacrificing its electrical property.

Significantly improved luminescence properties of nitrogen-polar (0001̅) InGaN multiple quantum wells grown by pulsed metalorganic chemical vapor deposition.

We have demonstrated nitrogen-polar (0001̅) (N-polar) InGaN multiple quantum wells (MQWs) with significantly improved luminescence properties prepared by pulsed metalorganic chemical vapor deposition. During the growth of InGaN quantum wells, Ga and N sources are alternately injected into the reactor to alter the surface stoichiometry. The influence of flow duration in pulsed growth mode on the luminescence properties has been studied.

Efficiency improvement of a vertical light-emitting diode through surface plasmon coupling and grating scattering.

The enhancement of output intensity, the generation of polarized output, and the reduction of the efficiency droop effect in a surface plasmon (SP) coupled vertical light-emitting diode (LED) with an Ag nano-grating structure located between the p-GaN layer and the wafer bonding metal for inducing SP coupling with the InGaN/GaN quantum wells (QWs) are demonstrated. In fabricating the vertical LED, the patterned sapphire substrate is removed with a photoelectrochemical liftoff technique. Based on the reflection measurement from the metal grating structure and the numerical simulation result, it is found that the localized surface plasmon (LSP) resonance induced around the metal grating crest plays the major role in the SP-QW coupling process although a hybrid mode of LSP and surface plasmon polariton can be generated in the coupling process.