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The superior crystalline quality of coaxial GaInN/GaN multiple-quantum shell (MQS) nanowires (NWs) was demonstrated by employing an AlGaN undershell during metal-organic chemical vapor deposition. Scanning transmission electron microscopy (STEM) results reveal that the NW structure consists of distinct GaInN/GaN regions on different positions of the NWs and the cores were dislocation-free. High-resolution atomic contrast STEM images verified the importance of AlGaN undershells in trapping the point defects diffused from n-core to MQSs (m-planes), as well as the improvement of the grown crystal quality on the apex region (c-planes). Time-integrated and time-resolved photoluminescence (PL) measurements were performed to clarify the mechanism of the emission within the coaxial GaInN/GaN MQS NWs. The improved internal quantum efficiency in the NW sample was attributed to the unique AlGaN undershell, which was able to suppress the point defects diffusion and reduce the dislocation densities on c-planes. Carrier lifetimes of 2.19 ns and 8.44 ns were derived from time-resolved PL decay curves for NW samples without and with the AlGaN undershell, respectively. Hence, the use of an AlGaN undershell exhibits promising improvement of optical properties for NW-based white and micro light-emitting diodes.

The aim of this research is to realize high‐efficiency light‐emitting diodes (LEDs) with a 3D core‐shell GaN nanowire. This article describes the growth of 3D core‐shell GaN nanowires, the formation of indium tin oxide (ITO) around the p‐GaN outer shell of the nanowires, and the characteristics of the fabricated nanowire‐LED (NW‐LED). The structural properties of the n‐GaN core, GaInN/GaN multiquantum shell (MQS), p‐GaN outer shell, and ITO electrode are investigated by scanning electron microscopy and scanning transmission electron microscopy. In addition, the optical and electrical characteristics of the NW‐LEDs are evaluated. The findings show that the grown n‐GaN cores have a uniform height and diameter, the MQS is defect‐free with a uniform film thickness, and p‐GaN outer shells with a uniform thickness are grown on both the m‐ and c‐planes. Consequently, a NW‐LED that emits light from the entire chip area is successfully realized by depositing an ITO electrode that covers the p‐GaN outer shells with a uniform film thickness. [ABSTRACT FROM AUTHOR]

The superior crystalline quality of coaxial GaInN/GaN multiple-quantum shell (MQS) nanowires (NWs) was demonstrated by employing an AlGaN undershell during metal-organic chemical vapor deposition. Scanning transmission electron microscopy (STEM) results reveal that the NW structure consists of distinct GaInN/GaN regions on different positions of the NWs and the cores were dislocation-free. High-resolution atomic contrast STEM images verified the importance of AlGaN undershells in trapping the point defects diffused from n-core to MQSs (m-planes), as well as the improvement of the grown crystal quality on the apex region (c-planes). Time-integrated and time-resolved photoluminescence (PL) measurements were performed to clarify the mechanism of the emission within the coaxial GaInN/GaN MQS NWs. The improved internal quantum efficiency in the NW sample was attributed to the unique AlGaN undershell, which was able to suppress the point defects diffusion and reduce the dislocation densities on c-planes. Carrier lifetimes of 2.19 ns and 8.44 ns were derived from time-resolved PL decay curves for NW samples without and with the AlGaN undershell, respectively. Hence, the use of an AlGaN undershell exhibits promising improvement of optical properties for NW-based white and micro light-emitting diodes. [ABSTRACT FROM AUTHOR]