The metal-organic chemical vapor deposition（MOCVD） growth of AlGaN/GaN distributed Bragg reflectors （DBR） with a reflection peak at 530 nm was in situ monitored using 633 nm laser reflectometry.Evolutions of in situ reflected reflectivity for different kinds of AlGaN/GaN DBR were simulated by the classical transfer matrix method.Two DBR samples,which have the same parameters as the simulated structures,were grown by MOCVD.The simulated and experimental results show that it is possible to evaluate the DBR parameters from the envelope shape of the in situ reflectivity spectrum.With the help of the 633 nm laser reflectometry,a DBR light emitting diode（LED） was grown.The room temperature photoluminescence spectra show that the reflection peak of the DBR in the LED is within the design region.
A monolithic white light-emitting diode （LED） with blue and yellow light active regions has been designed and studied. With the AlxGa1-xN/InyGa1-yN distributed Bragg reflector （DBR） resonant-cavity, the extraction efficiency and power of the yellow light are enhanced so that high quality white light can be obtained.
The enhancement of the light output of an embedded photonic crystal light emitting diode is investigated based on the finite-difference time-domain modeling. The embedded photonic crystal （PC） lattice type, multi-layer embedded PC, distance between the multiple quantum well and the embedded PC are studied. It is found that the embedded one dimensional PC can act as well as embedded two dimensional PCs. The emitted light flux in the up direction can be increased by a new kind of multi-layer embedded PC. Also, we show that the light output in the up direction for the LED with both surfaces and embedded PC could be as high as five times that of a conventional LED.
A two-electrode multi-quantum-well semiconductor optical amplifier is designed and fabricated.The amplified spontaneous emission（ASE）spectrum and gain were measured and analyzed.It is shown that the ASE spectrum and gain characteristic are greatly influenced by the distribution of the injection current density.By changing the injection current density of two electrodes,the full width at half maximum,peak wavelength,peak power of the ASE spectrum and the gain characteristic can be easily controlled.
