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Highlights: [•] A nanoporous InGaN/GaN multiple quantum wells has been fabricated. [•] The overall external quantum efficiency for nanoporous InGaN/GaN MQWs is enhanced. [•] The nanoporous structure led to more light scattering and lower defects density. [Copyright &y& Elsevier]

Abstract: InGaN/GaN single quantum well (SQW) structures under various InGaN growth temperatures have been grown by metal organic chemical vapor deposition (MOCVD), the surface morphologies and optical properties are investigated. The radius of the typical V-pits on the SQW surface is affected by the InGaN well-temperature, and the surface roughness decreased as the well-temperature reduced. Room-temperature photoluminescence (PL) and cathode luminescence (CL) shows the quantum well and quantum dot (QD)-like localized state light emission of the SQWs grown at 700 and 690°C, respectively, whereas the samples grown at 670 and 650°C present hybrid emission peaks. Excitation power dependent PL spectra indicates the QD-like localized state emission dominates at low excitation power and the quantum well emission starts to take over at high excitation power. [Copyright &y& Elsevier]

Abstract: By solving Schrödinger and Poisson equations self-consistently for Al x Ga1−x N/GaN heterostructures grown along the axis, the spatial distribution of electrons and the energy of all the bound states confined in heterostructures are obtained, and electrons are found to occupy the first two subbands. Considerable magnitude of the Rashba spin splitting for the first two subbands at the Fermi level is obtained. Changes of the Rashba spin splitting with the Al composition in the barrier are calculated. The effect of electrons taking up more than one subband on the Rashba spin splitting for the first subband is discussed. Individual factors contributing to the Rashba spin splitting are discussed in detail, and the contribution to the Rashba coefficient from the well and the heterointerface are found to be much more than that from the barrier. The results show that a high density of the 2DEG and the internal electric field caused by the piezoelectric polarization and the spontaneous polarization are crucial for considerable Rashba spin splitting for Al x Ga1−x N/GaN heterostructures. [Copyright &y& Elsevier]