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The development of high-productivity microLED (μ-LED) pixel panels is crucial as a key technology for next-generation displays. To provide a fundamental approach to this end, in this study, multicolor (red, green, blue, and yellow; RGBY) nanocolumn (NC) μ-LED pixels with 5 × 5 μm2 emission windows were monolithically integrated to exhibit electroluminescence spectra with peak wavelengths of 478, 512, 559, and 647 nm, respectively. The NC μ-LED pixels, which were two-dimensionally arranged with a 10 μm period, were individually driven by the matrix wiring p- and n-electrodes, exhibiting a μ-LED pixel panel arrangement.

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The influence of GaN column diameter DGaN on structural properties was systematically investigated for InGaN nanocolumns (NCs) grown on top of GaN NCs. We demonstrated a large critical layer thickness of above 400 nm for In0.3Ga0.7N/GaN NCs. The structural properties were changed at the boundary of DGaN=D0 (∼120 nm). Homogeneous InGaN NCs grew axially on the GaN NCs with DGaN≤D0, while InGaN-InGaN core-shell structures were spontaneously formed on the GaN NCs with DGaN>D0. These results can be explained by a growth system that minimizes the total strain energy of the NCs.

The design process of superluminescent diode has been discussed on the basis of nitride diodes with bend-waveguide geometry. The devices were fabricated by MOVPE technique on bulk GaN substrates and emitted light at the wavelength of around 420 nm. The effectiveness of the cavity suppression design was confirmed by measurements of high-resolution emission spectra. Further optimization was carried out by appropriate selection of the angles of the waveguide bend and the chip length. Thus; we succeeded in fabrication of high optical power superluminescent diodes with slope efficiency fully comparable to that of laser diodes (greater than 0.9 W/A).Comparison of emission spectra of a superluminescent diode and a laser diode.