Effects of GaN cap layer thickness on photoexcited carrier density in green luminescent InGaN multiple quantum wells

• Published in: Japanese Journal of Applied Physics Vol. 62; no. 3; pp. 31001 - 31006
• Main Authors: Murotani, Hideaki, Nakatsuru, Keigo, Kurai, Satoshi, Okada, Narihito, Yano, Yoshiki, Koseki, Shuichi, Piao, Guanxi, Yamada, Yoichi
• Format: Journal Article
• Language: English
• Published: Tokyo IOP Publishing 01.03.2023; Japanese Journal of Applied Physics
• Subjects: Barrier layers; Carrier density; Electric field strength; Excitation; GaN cap layer; Indium gallium nitrides; InGaN; MQW; Multi Quantum Wells; Optical properties; Photoluminescence; Quantum efficiency; Thickness
• ISSN: 0021-4922; 1347-4065
• DOI: 10.35848/1347-4065/acc4fd

Abstract The effects of GaN cap layers on the optical properties of green luminescent InGaN-based multiple quantum wells were studied by photoluminescence (PL) spectroscopy. The PL peak energy under the selective excitation of the InGaN well layers was lower than that under the band-to-band excitation of the GaN barrier layers. The difference in the PL peak energies between the selective and band-to-band excitations decreased as the cap layer thickness increased, indicating an increase in the nonradiative recombination of photogenerated carriers in the barrier layers. Moreover, the internal quantum efficiency under selective excitation decreased as the cap layer thickness increased because of the increase in the internal electric field strength.