Epitaxial Growth And Performance Of V-shaped Pits And P-shaped Insertion Layers In GaN-based Light-emitting Diodes

GaN based light emitting diodes(LEDs)have been widely used,but the rapid growth of the market requires higher and higher quality of LED products.During the epitaxial growth of GaN based LED,it is found that the potential barrier generated by V-pits can shield dislocations,so it is an effective method to improve the luminous efficiency of LED.At the same time,device reliability is also very important for the application of GaN based LED.Therefore,this paper studies the influence of V-pits on the reliability of GaN based LED by adjusting the epitaxial growth of V-pits;The low temperature p-type insertion layer technology is also compared and analyzed to study its influence on the luminous efficiency of LED.This paper studies the epitaxial growth process based on the traditional GaN Blue LED process.The main works are as follows:1.The influence of V-pits in GaN based LED on the antistatic performance(ESD)of the device is studied and analyzed.GaN based LED devices with different sizes of v-pits were obtained by adjusting the growth thickness of GaN barrier layer in stress buffer layer.The analysis results show that the size of v-pits structure is in the range of 100 to 200 microns,and the GaN based LED device with larger V-pits structure has higher reliability.Under the test voltage of-4000 V,when the size of V-pits increases,the ESD yield increases from 4.23%to 98.67%,and the ESD yield increases significantly.When the device is subjected to electrostatic discharge,V-pits can provide current channel,increase the distribution density of current channel,reduce the current density of the main light-emitting region of the device,and then reduce the probability of thermal breakdown in the light-emitting region.The band gap of V-pits sidewall quantum wells is greater than that of c-plane quantum wells under normal operating voltage,which reduces the probability of carrier aggregation at the bottom dislocation of V-pits,so as to improve the reliability of the device.2.The influence of low temperature p-type insertion layer on the device performance of GaN based LED is studied and analyzed.The existence of V-pits has a positive effect on the improvement of LED performance.Large V-pits structure needs high-quality p-type coating to cover defects,so as to obtain flat surface morphology.The high-quality p-type coating with good defect coverage effect generally needs to maintain the growth temperature at about 1000?.However,the growth temperature of GaN based LED multi quantum well(MQW)active layer is generally about 800?,and the temperature required for the growth of high-quality p-type cladding layer is significantly higher than that of multi quantum well(MQW)active layer.The high temperature of growing p-type cladding layer will affect the content and distribution of indium in the last few pairs of active layers,resulting in decomposition and segregation.Due to the influence of electron hole mobility and hole injection efficiency,the radiation recombination of electrons and holes in GaN based LED is mainly concentrated in quantum wells close to p-type cladding.The growth position of the p-type cladding layer is behind the active layer of the quantum well.The high temperature required for its growth has the greatest impact on the quantum well close to the p-type cladding layer,which has a great impact on the luminous efficiency of the LED.This problem is well solved by introducing low-temperature p-type insertion layer technology.Compared with the samples without low-temperature p-type insertion layer,the light efficiency is greatly improved.In this paper,the action principle of low-temperature p-type insertion layer is compared and studied.By adjusting and analyzing the growth time and temperature of low-temperature p-type insertion layer,the optimal growth conditions are obtained.Through the epitaxial growth and performance study of V-pits and low-temperature p-type insertion layer in GaN based LED,GaN based LED epitaxial wafers with high reliability and high luminous efficiency can be obtained.The antistatic performance and luminous efficiency of GaN based LED prepared by this process can be significantly improved.Relevant research has guiding and reference significance for industrial epitaxial growth.