Performance of GaN-based light-emitting diodes fabricated using GaN epilayers grown on silicon substrates.

Ray-Hua Horng,Sin-Liang Ou,Ching-Ho Tien,Hao-Chung Kuo,Bing-Rui Wu,Min-Hao Yang,Dong-Sing Wuu

doi:10.1364/oe.22.00a179

Abstract

Light extraction of GaN-based light-emitting diodes grown on Si(111) substrate (GaN-on-Si based LEDs) is presented in this study. Three different designs of GaN-on-Si based LEDs with the lateral structure, lateral structure on mirror/Si(100) substrate, and vertical structure on mirror/Si(100) substrate were epitaxially grown by metalorganic chemical vapor deposition and fabricated using chemical lift-off and double-transfer techniques. Current-voltage, light output power, far-field radiation patterns, and electroluminescence characteristics of these three LEDs were discussed. At an injection current of 700 mA, the output powers of LEDs with the lateral structure on mirror/Si(100) substrate and vertical structure on mirror/Si(100) substrate were measured to be 155.07 and 261.07 mW, respectively. The output powers of these two LEDs had 70.63% and 187.26% enhancement compared to that of LED with the lateral structure, respectively. The result indicated this vertical structure LED was useful in improving the light extraction due to an enhancement in light scattering efficiency while the high-reflection mirror and diffuse surfaces were employed.

Highlights

GaN-based light-emitting diodes grown on silicon substrate (GaN-on-Si based LEDs) are thought to be one of the most promising choices for high power LEDs applications owing to the numerous advantages of Si substrate, such as low manufacturing cost, good thermal and electrical conductivities, large scale availability with high quality, and the possibility of integration for Si electronics on the same chip [1,2,3,4]
It is found that the increments in output power (@ 700 mA) of VS-LED and DT-LED are further increased to 187.26% and 70.63%, respectively, as compared with that of LS-LED
The performance of the GaN-based LEDs grown on Si(111) substrate is further improved by transferring the device to Si(100) substrate using the chemical lift-off (CLO) and double-transfer techniques

Summary

Introduction

GaN-based light-emitting diodes grown on silicon substrate (GaN-on-Si based LEDs) are thought to be one of the most promising choices for high power LEDs applications owing to the numerous advantages of Si substrate, such as low manufacturing cost, good thermal and electrical conductivities, large scale availability with high quality, and the possibility of integration for Si electronics on the same chip [1,2,3,4]. The cracks are created when the thickness of GaN epilayer exceeds the critical value around 1 μm [5, 6] To solve these problems, several intensive researches have been dedicated to the optimization for the epitaxial growth of GaN-on-Si, especially for the stress management and crack reduction in the epilayer [2,3,4, 7,8,9,10,11]. Several intensive researches have been dedicated to the optimization for the epitaxial growth of GaN-on-Si, especially for the stress management and crack reduction in the epilayer [2,3,4, 7,8,9,10,11] Among these approaches, the employment of nucleation buffer layers [e.g. aluminum nitride (AlN) or aluminum gallium nitride (AlxGa1−xN) graded layers] on Si substrates is a prospective technique to counterbalance the thermally induced tensile strains for subsequent growth of crack-free GaN epilayers. We demonstrate greatly improved optical and electrical properties of the lateral-type GaN-based LEDs on mirror/Si(100) substrate and vertical-type GaN-based LEDs on mirror/Si(100) substrate compared with the original lateral devices

Experimental

Findings

Result and discussion

Conclusion