The Research On Improving The Efficiency Of LED Based On Nanostructure

As a new generation of semiconductor material,GaN has the advantages of larger band gap,higher thermal conductivity,higher carrier mobility,higher luminous efficiency,etc,being an ideal material of the preparation of short wavelength LED devices.With the advantage of energy conservation and environment protection,faster response,small volume,higher efficiency,etc,GaN-LED has been extensive used in solid state lighting,backlight devices and so on.However the development of GaN-LED is still facing with many challenges,such as the efficiency droop phenomenon that the efficiency of LED descends gradually as the injection current increases.The exact origin of such phenomenon is still not fully understood.Serval loss mechanisms to explain the efficiency droop have been proposed such as carrier leakage,low efficiency of carrier injection,Auger recombination and junction heating.The reduction of efficiency droop is one of the key issues to improve the performance of GaN-LED devices.In this paper,firstly,the development of light-emitting diodes and its research status and research significance are displayed;secondly,the basic properties of GaN material,the electron blocking layer,the multi-quantum wells and efficiency droop phenomenon in particular are been discussed;then,the basic knowledge of APSYS software is shown as well as the basic models and theories for the numerical modeling;finally,the numerical simulation data we got and the proposed InGaN/AlGaN/GaN multi-quantum well electron blocking layer is discussed.Through the analysis of data,it is shown that the InGaN/AlGaN/GaN EBL has a great effect on improving the optical properties and electrical properties of the LED device.With the larger effective barrier height,it is found that LEDs with InGaN/AlGaN/GaN EBL exhibit smaller carrier leakage,at the same time,the density of electrons and holes are increased and the distribution of electrons and holes in the multi-quantum well active region is much more even.It is found that the proposed LED's power and internal quantum efficiency are improved about 12.7% and 12.3% respectively at the current of 156 mA.Furthermore,the efficiency droop is decreased effectively from about 37.1% in conventional LED to about 31.1% in proposed LED at the current of 156 mA and the maximal internal quantum efficiency is increased from 0.817 to 0.838.With the application of InGaN/AlGaN/GaN EBL,the light output power,the internal quantum efficiency and the barrier height are all increased which means the InGaN/AlGaN/GaN EBL could effectively reduce efficiency droop.