Study On Optoelectronic Properties And Reliability Of Ga N-based LEDs On Si Substrate

LED based on GaN, with its controllable panchromatic spectrum as well as excellent physical and chemical properties, has broad application prospects in a variety of areas such as lighting, backlighting and has gradually become the new generation of green illumination photosource. The current the mainstream technology program of LED illumination is the "blue LED + yellow phosphor" synthetic white LED, although you can get a higher luminous efficiency, isochromatic quality such as the color warm and the colored index is not good. In order to obtain a high-quality LED lighting in the true sense, white light requires a full LED mixed light, namely the use of red, green, blue three primary color LED(RGB) to obtain white light, so that you can achieve the perfect combination of low color temperature, high color rendering index as well as high efficiency. At present, the luminous efficiency of green light LED is far behind the blue and red LED, it is called "Green gap" in the academic circles, which has become a main technical bottlenecks to achieve RGB white light sources. Therefore, further advancing the green light LED quantum efficiency become a hot topic the field of LED in recent years. This article study the thickness of electron blocking layer(EBL)which close to the last quantum well of silicon substrate green light LED effects on many characteristics such as light output power(LOP)and working voltage(VF2),But the thickness of p-GaN is not changed. In addition this paper summary the relationship about the observation of the surface morphology with the monitoring concentration of Mg doped in p-GaN,At the same time this paper summary the change about IR in the process of aging. The following research results:1、We optimize the thickness of electron blocking layer(EBL)which closes to the last quantum well of silicon substrate green light LED effects on many characteristics,But the thickness of p-GaN is not changed. And we also done a lot of reliability test. The light output power(LOP) is found to be higher in the 350 mA current when EBL is combined with a p-AlGaN of 200 ? and a p-In GaN of 400 ?, and there is not much difference between the working voltage(VF2) of the four experimental samplesin the 350 mA current. It has a good optical and electrical properties. The reason that the light output power when has high current rise is the strong static electric field which formed with electronic interference, scattering or reflecting. The band of the last barrier which bend down because of the static electric field of GaN rise by the strong static electric field. This can increase the barrier height of void,at the same time it also reduce the barrier of electronics.2、The voltage of chip will rise if the concentration of Mg doped in p-GaN is high. So we need to monitor the concentration of Mg doped in p-GaN. We found that the stair is irregular in the context of 10 micrometer when the high concentration of Mg doped in p-GaN through tracking the concentration of doped Mg and observing the surface of the thin film for a long time,And there will be some white spots which like small hills. We cannot see the white spot when the scanning range is increased to 2 micrometer. We characterizes the concentration of Mg doped in p-GaN with secondary ion mass spectroscopy(SIMS),The results showed that the concentration of doped Mg in p-GaN in the thin film appeared white spots is really high. Therefore, We propose a quick and easy method monitoring concentration of Mg doped in p-GaN from using the AFM according to the corresponding relation between the scan of AFM and SIMS。3、We strictly screen the chip about different IR from the source of the film and the chip process,Through a large number of aging test which compared with the change of IR when the voltage is-5 in the I-V characteristic curve,We found that the chip which IR is less than 0.05 μA is relatively stable in the process of aging, We can screen out the high quality chip through the static loading ESD of 300 V.We also found that the chip which IR is from 0.05 μA to 0.1μA is not relatively stable in the process of aging,We can screen out the high quality chip only through above loading ESD of 1000 V.The chip which IR is from 0.1 μA to 1 μA is very bad in the process of aging,And it is difficult to select the high quality chip. We can screen the high quality chip through the smaller static test ESD Test Electrostatic Discharge and IR controlled with smaller inner,which is a very effective method for selecting high quality chip.