Au-Zn,TiPdAu电极对InGaAsP/InP双异质结发光管可靠性影响的研究

Au-Zn,TiPdAu ELECTRODE INFLUENCE ON THE RELIABILITY OF InGaAsP/InP LED's

本文用AES研究了P-InP/TiPdAu热处理前后的界面特性,结果表明:TiPd层对Au的内扩散和In的扩散有阻挡作用。以TiPdAu作InGaAsP/InP双异质结发光管的p面电极、镀Au作热沉,采用In焊料,研究了器件的可靠性问题,在室温大气气氛中;70℃存储,70～80℃带电老化,三种条件下长时间考核结果表明:器件的I-V特性正常,末见正向压降明显变化。还比较了Au-Zn材料作p面电极用TiPdAu作肖脱基势垒限制层制成的器件和用TiPdAu作电极材料制成的深Zn扩散型器件在老化过程中的特性变化,后二种结构的器件,在长期老化过程中,有源区中有大面积DSD生长和增殖。

The interdiffusion of the P-InP with TiPdAu and Au-Zn at interface has been investigated by Auger electron spectroscopy. The results incidate that Ti -and Pd layer as a diffusion barrier plays and important role. The TiPdAu layer is used as the P-electrode of InGaAsP/InP double heterojunction light emitting diodes. The InGaAsP/InP DH wafers were grown by LPE technique. It consisted of three or four layers. The first layer of n-InP was the buffer layer doped with Sn or Te 5-8μm; the second one was an undoped active layer (1-2μm); the third was confining layer of p-InP doped with Zn (2~3μm), and the last was Zn doped contact layer, with the plated Au as heat sink. The InGaAsP/InP DH LED's were soldered with In onto Au-plated heat sink. The reliability of devices were investigated at the room temperature, 70℃ and 85℃ with and without inject current respectively. The experiment was carried out in air. The I-V characteristics of the devices were measured during the aging test. The dark defect in the LED's were observed with an infrared line scanner.The results show that no change of the I-V characteristics is observed. It indicates that the InGaAsP/InP DH LED's made of the TiPdAu as p-electrode have high reliability. The devices made cf the Au-Zn as p-electrode or deep Zn diffusion are different from the devices made of TiPdAu as p-electrode. In the former the large DSD's are generated in the emitting area during aging.