Monolithically integrated green-to-orange color InGaN-based nanocolumn photonic crystal LEDs with directional radiation beam profiles

In this study, the monolithic integration of LEDs with different emission colors (wavelengths of 543, 573, and 597 nm) with the directional radiation profiles was demonstrated. InGaN/GaN nanocolumn arrays ordered in a triangular lattice were prepared side by side, changing the diameter of the n-GaN nanocolumn (Dn-GaN). The periodic arrangement of the nanocolumns led to the photonic crystal (PC) effect. The photonic band edge wavelength (λB) and the InGaN bandgap were controlled by the Dn-GaN. By controlling λB closely at the bandgap wavelength, the PC effect provided directional beam radiation from the LEDs with radiation angles of approximately ±30°