[11a-W541-1~12] 15.4 III-V-group nitride crystals

[11a-W541-3] Structural characteristics of AlGaN multiple-quantum-wells grown on c-plane AlN/sapphire templates with macro-steps (2)

〇Yosuke Nagasawa¹, Kazunobu Kojima², Akira Hirano¹, Masamichi Ipponmatsu¹, Yoshio Honda³, Hiroshi Amano³, Isamu Akasaki⁴, Shegefusa Chichibu² (1.UV Craftory, 2.Tohoku Univ.-IMRAM, 3.Nagoya Univ.-IMaSS, 4.Meijo Univ.)

Keywords:AlGaN, AlGaN MQWs

Optical properties of AlGaN multiple-quantum-wells designed for deep-ultraviolet light emitting diodes (DUV LEDs) with 285 nm wavelength are investigated by comparing with the 260 nm wavelength sample. The growth of the samples was carried out using a metalorganic vapor phase epitaxy method. An AlN template having macro-steps was grown on c-plane sapphire with miscut angle of 1.0 degree to m-axis. An n-type AlGaN:Si layer, three quantum well layers and an electron blocking layer were subsequently fabricated. Cathodoluminescence (CL) mappings were obtained by measuring with 50 nm pitch. The CL peak intensity mappings of the 260 and 285 nm samples show that bright zones were located near the step edges. For the 285 nm sample, bright zones were observed on some terraces whereas for the 260 nm sample, no bright zone was seen on the terraces. It was estimated that the internal quantum efficiency of 285 nm DUV LEDs grown on the templates having macro-steps is higher than that of 260 nm devices. The contributions of the CL intense zones of the terraces as well as the edges could explain the trend of the luminescence efficiencies.