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A strong polarization electric field (PEF) in III‐nitride semiconductors has adverse effects on the performance of III‐N light‐emitting diodes (LEDs). However, to reduce the PEF of III‐N LEDs based on the polar plane (c‐plane) remains a big challenge. Here, a weak PEF blue LED on c‐plane GaN with an InGaN/AlGaN superlattices (SLs) quantum barrier and InGaN quantum well grown by metal‐organic chemical vapor deposition is proposed. The InGaN/SLs multiple quantum wells (MQWs) show a significant reduction of PEF compared with traditional InGaN/GaN MQWs. A low electric field of 0.5 MV cm−1 is obtained, which is confirmed by power‐dependent photoluminescence (PL) and time‐resolved PL measurements. The proposed LEDs with InGaN/AlGaN SLs barriers present a low efficiency droop, a great wavelength stability, and a high −3 dB E‐O modulation bandwidth up to 1.01 GHz. This work demonstrates the role of InGaN/AlGaN SLs barriers in reducing the PEF of III‐N LEDs and provides a feasible technical route to achieve the weak PEF LEDs on c‐plane, which can be expanded and applied to the preparation of high‐performance, long wavelength, and deep UV III‐N LEDs. [ABSTRACT FROM AUTHOR]

Nitrogen-polar (N-polar) III-nitride has natural advantages in the fabrication of electronic devices. In this work, unintentionally doped N-polar GaN films were grown on sapphire substrates by metalorganic chemical vapor deposition. By optimizing the growth parameters including growth temperature, pressure, and V/III ratio, N-polar GaN with a relatively high sheet resistivity of 3.6 × 105 Ω/sq was achieved. The secondary ion mass spectroscopy and x-ray diffraction measurement results demonstrate that the increased carbon impurity concentration is primarily responsible for the high resistivity. Moreover, N-polar GaN/Al0.25Ga0.75N heterojunctions were deposited on the high-resistivity N-polar GaN template. An extremely high-density two-dimensional electron gas of up to 1.12 × 1013 cm−2 was realized at the interface between the Al0.25Ga0.75N and the GaN. It is reasonably believed that the experimental results obtained here are beneficial for the development of high-performance N-polar GaN-based electronic devices. [ABSTRACT FROM AUTHOR]

• A two-step high-temperature growth method was adopted to grow N-polar GaN. • The influence of growth parameters on the properties of N-polar GaN was analyzed. • N-polar GaN with both smooth surface and high crystalline quality was achieved. Normally, nitrogen-polar (N-polar) GaN films with better crystalline quality tend to have poor surface morphology, whereas those with good surface morphology suffer from degraded crystalline quality. In this work, we use a two-step high-temperature (HT) growth method to grow N-polar GaN films on vicinal c-plane sapphire substrates by metalorganic chemical vapor deposition, which can effectively solve the irreconcilability between surface morphology and crystalline quality. The GaN film consists of two GaN layers (HT-GaN 1 and HT-GaN 2), which were grown at different growth parameters, respectively. The 300-nm-thick HT-GaN 1 layer was directly grown on the low-temperature GaN buffer layer under the higher V/III ratio and pressure at 1040 °C to reduce dislocation density. The 1.7-μm-thick HT-GaN 2 layer was grown under the lower V/III ratio and pressure to improve surface morphology. Besides, the growth temperature of HT-GaN 2 layer was ramped up to 1070 °C to suppress the yellow-band luminescence. Finally, high-quality N-polar GaN films with smooth surface morphology and high crystalline quality were obtained, for which the full-width at half-maximum values of (0002) and (10 1 ¯ 2) planes X-ray diffraction rocking curves are 131 and 390 arcsec, respectively, the root mean square roughness over an area of 20 × 20 μm2 is 1.88 nm, and the residual compressive stress is as low as 0.025 GPa. It is reasonably believed that this work provides an effective approach to preparing high-quality N-polar GaN films for the application of N-polar nitride devices. [ABSTRACT FROM AUTHOR]