講演情報
[8a-N301-4]High Quality of DC-sputtered AlN Assisted by High Temperature Annealing and Demonstration of 0.42% Efficient far-UVC LED
〇Muhammad Ajmal Khan1, Yuya Nagata1,2, Kohei Fujimoto1,2, Hiromitsu Sakai3, Yukio Kashima1, Eriko Matsuura1, Hiroyuki Yaguchi2, Atsushi Maeoka4, Atsushi Osawa4, Hideki Hirayama1 (1.RIKEN, Japan, 2.Saitama Univ., Japan, 3.Shin-Etsu Chemical Japan, 4.SCREEN Holdings Co., Ltd Japan)
キーワード：
Dc-sputtered AlN、High temperature annealing、fa-UVC LED
RF sputtering technique for AlN face to AlN during high-temperature annealing was used for far-UVC LED, where EQE of 0.4% on wafer was achieved. In this work, we aim to improve the quality of AlN templates by using DC sputtering and high-temperature annealing 1730 °C, of 500 nm-thick AlN on c-Sapphire substrates. As the DC Sp-AlN film thickness increased, the full width at half maximum of XRD rocking curves along 002 plane and 102 plane, respectively, decreased to 70 arcsecs and 127 arcsecs. However, when the thickness of AlN exceeds 800 nm, high density cracking occurs, and the surface is roughened. The crystalline and surface were improved as the temperature increased, but at temperatures above 1720 °C, there was a serious problem of face-to-face Sp-AlN to Sp-AlN sticking to each other. To solve this problem, we introduced a novel method of HTA by facing DC sputtered AlN to a dissimilar substrate at temperatures above 1730 ºC. As a result, the FWHM of XRCs along 002 planes and 102 planes, respectively, were remarkably improved to a world record value of 49 arcsec and 89 arcsec without sticking. Finally, 231nm far-UVC LEDs were successfully grown on DC-sp-AlN-HTA, and light output power of 2 mW under CW and 3 mW, and EQE of 0.42% on bare wafer at RT were achieved.