InGaN/GaN superlattice underlayer for fabricating of red nanocolumn μ-LEDs with (10-11) plane InGaN/AlGaN MQWs

Jumpei Yamada; Ai Mizuno; Tatsuya Honda; Keigo Yoshida; Rie Togashi; Ichirou Nomura; Tomohiro Yamaguchi; Tohru Honda; Katsumi Kishino

doi:10.1088/1361-6528/acea88

InGaN/GaN superlattice underlayer for fabricating of red nanocolumn μ-LEDs with (10-11) plane InGaN/AlGaN MQWs

Nanotechnology. 2023 Aug 14;34(43). doi: 10.1088/1361-6528/acea88.

Authors

Jumpei Yamada¹, Ai Mizuno¹, Tatsuya Honda¹, Keigo Yoshida², Rie Togashi¹, Ichirou Nomura¹, Tomohiro Yamaguchi², Tohru Honda², Katsumi Kishino¹

Affiliations

¹ Nanotechnology Research Center, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo, Japan.
² Department of Applied Physics, Kogakuin University, 2665-1 Nakanomachi, Hachioji-Shi, Tokyo, Japan.

PMID: 37494895
DOI: 10.1088/1361-6528/acea88

Abstract

In this study, the growth behavior of Indium gallium nitride (InGaN)-based nanocolumn arrays was investigated, and red emission nanocolumn micro-light emitting diodes (μ-LEDs) were fabricated. The internal structure of the InGaN/GaN superlattice (SL) layer under the multiple-quantum-well (MQW) active layers was evaluated using scanning transmission electron microscopy (STEM) analysis. It was revealed that the InGaN crystal plane at the top of the nanocolumn changed from the c-plane, (1-102) plane, to the (10-11) plane as the number of SL pairs increased. A semipolar (10-11) plane was completely formed on top of the nanocolumn by growing InGaN/GaN SLs over 15-20 pairs, where the InGaN/GaN SL layers were uniformly piled up, maintaining the (10-11) plane. Therefore, when InGaN/AlGaN MQWs were grown on the (10-11) plane InGaN/GaN SL layer, the growth of the (10-11) plane semipolar InGaN active layers was observed in the high-angle annular dark field (HAADF)-STEM image. Moreover, the acute nanocolumn top of the (10-11) plane of the InGaN/GaN SL underlayer did not contribute to the formation of the c-plane InGaN core region. Red nanocolumnμ-LEDs with anφ12μm emission window were fabricated using the (10-11) plane MQWs to obtain the external quantum efficiency of 1.01% at 51 A cm^-2. The process of nanocolumnμ-LEDs suitable for the smaller emission windows was provided, where the flat p-GaN contact layer contributed to forming a fine emission window ofφ5μm.

Keywords: InGaN; MBE; micro-LED; nanocolumn; semipolar.