Ultralow threading dislocation density in GaN epilayer on near-strain-free GaN compliant buffer layer and its applications in hetero-epitaxial LEDs

Huan-Yu Shih; Makoto Shiojiri; Ching-Hsiang Chen; Sheng-Fu Yu; Chung-Ting Ko; Jer-Ren Yang; Ray-Ming Lin; Miin-Jang Chen

doi:10.1038/srep13671

Ultralow threading dislocation density in GaN epilayer on near-strain-free GaN compliant buffer layer and its applications in hetero-epitaxial LEDs

Sci Rep. 2015 Sep 2:5:13671. doi: 10.1038/srep13671.

Authors

Huan-Yu Shih¹, Makoto Shiojiri², Ching-Hsiang Chen³, Sheng-Fu Yu⁴, Chung-Ting Ko¹, Jer-Ren Yang¹, Ray-Ming Lin⁴, Miin-Jang Chen¹

Affiliations

¹ Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan.
² Kyoto Institute of Technology, Kyoto, Japan.
³ Graduate Institute of Applied Science &Technology, National Taiwan University of Science &Technology, Taipei, Taiwan.
⁴ Department of Electronic Engineering, Chang Gung University, Taoyuan, Taiwan.

Abstract

High threading dislocation (TD) density in GaN-based devices is a long unresolved problem because of the large lattice mismatch between GaN and the substrate, which causes a major obstacle for the further improvement of next-generation high-efficiency solid-state lighting and high-power electronics. Here, we report InGaN/GaN LEDs with ultralow TD density and improved efficiency on a sapphire substrate, on which a near strain-free GaN compliant buffer layer was grown by remote plasma atomic layer deposition. This "compliant" buffer layer is capable of relaxing strain due to the absorption of misfit dislocations in a region within ~10 nm from the interface, leading to a high-quality overlying GaN epilayer with an unusual TD density as low as 2.2 × 10(5) cm(-2). In addition, this GaN compliant buffer layer exhibits excellent uniformity up to a 6" wafer, revealing a promising means to realize large-area GaN hetero-epitaxy for efficient LEDs and high-power transistors.