利用湿法腐蚀提高红光LED外延片的发光效率

Enhancement of Extraction Efficiency of Red LED via Wet Surface Roughening

采用熔融态的KOH对AlGaInP基红光LED外延片进行了表面粗化处理。研究了粗化温度、粗化时间对LED外延片表面形貌的影响,并利用原子力显微镜(AFM)、半导体芯片自动测试系统对LED器件的相关性能(形貌、I-V特性曲线、亮度和主波长)进行了表征。比较了粗化前后的LED亮度和电流特性变化。测试结果表明:利用熔融态的KOH对AlGaInP基红光LED外延片进行表面粗化可以有效地抑制光在通过LED表面与空气接触界面时产生的全反射,得到性能更好的器件。实验结果显示,采用熔融态KOH,在粗化温度为200℃、粗化时间为8min时,能使制作的红光LED外延片发光效率提高30%。

In this paper,the surface of red LED epitaxial wafer was roughened with molten KOH.The effects of molten KOH at different temperature and different roughening time on the surface morphology of the LED epitaxial wafer were analyzed.And the performance indexes such as morphology,I-Vcharacteristic curves,brightness and dominant wavelength,of LED devices were characterized by atomic force microscope and semiconductor chip automatic characterization system.The brightness and current characteristics of LED devices before and after roughening were compared.The results show that using molten KOH to rough LED epitaxial wafers can effectively suppress the total reflection of the light passing through the interface of LED surface and air.Experimental results show that the luminous efficiency of the red LED epitaxial wafer is improved by about 30%after being etched in 200℃ molten KOH for 8min.