Research On White-light LED Array Based On A GaN Nanorod Structure

Recently,the gallium nitride(GaN)nanorod as the potential building blocks for integrated photonic device has attracted wide attention.Compare to other semiconductor materials such as silicon(Si),gallium arsenide(GaAs),indium phosphide(InP),the growth of GaN nanorod is self-catalyzed,and the unwanted catalysis contamination to the nanorod is eliminated.Moreover,the nitride is in harmony with the environment compared with arsenic and phosphine.This paper is aimed at the country's strategic demand for clean energy.The environment-friendly white-light LED device based on InGaN/GaN heterostructure nanorods is proposed with high efficiency and stable performance.In this paper,by introducing a GaN nanorod structure into the LED device,the escaping angle of the emitted photon is increased,and the optical energy loss due to total reflection is reduced.Meanwhile,the optical beam guiding effect of the nanorod structure can further improve the light extraction efficiency of the luminescent material.Second,as the InGaN quantum well structure is grown on a non-polarized m-plane of nanorod sidewalls,the quantum confinement stark effect(QCSE)can be completely eliminated,and the internal quantum efficiency of the device is greatly improved.Third,by optimizing the height,raidus and top surface area of the nanorod,the content of indium(In)in the InGaN quantum well could be tuned.Hence,by carefully choosing geometric parameters of two-section NR,blue light emission at the NR lower section and yellow light emission at the upper section can be realized,which results in whitelight output.Based on the optimized parameters,the device properties such as luminescence spectrum,turn-on voltage,full width at half maximum(FWHM)and relative radiance of LED were simulated.Finally,the current-driven analysis of the spectrum shows that the yellow and blue spectra have a slight blue shift as the current increases,and the FWHM of the yellow light is always greater than that of the blue light.The second part of this paper analyzes the radiation characteristics of nanorod structure models.It is found the emission intensity of the upper section is higher than of lower section under the same applied voltage.As the increment of apply voltage,the emission intensity for both the upper and lower section of NR increases as well.Then,the radiances characteristic of the single-layer and double-layer quantum wells were compared,and the double-layer quantum wells were found to have higher emissivity.Therefore,the proposed structure are regarded as promising candidates in phosphorfree white-light emission LED.