Ultralow threading dislocation density in GaN epilayer on near-strain-free GaN compliant buffer layer and its applications in hetero-epitaxial LEDs.
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.
Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan.
Huan-Yu
HY
Shih
Kyoto Institute of Technology, Kyoto, Japan.
Makoto
M
Shiojiri
Graduate Institute of Applied Science &Technology, National Taiwan University of Science &Technology, Taipei, Taiwan.
Ching-Hsiang
CH
Chen
Department of Electronic Engineering, Chang Gung University, Taoyuan, Taiwan.
Sheng-Fu
SF
Yu
Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan.
Chung-Ting
CT
Ko
Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan.
Jer-Ren
JR
Yang
Department of Electronic Engineering, Chang Gung University, Taoyuan, Taiwan.
Ray-Ming
RM
Lin
Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan.
Miin-Jang
MJ
Chen