Anatase Nb-doped TiO2 transparent conducting oxide has been formed on GaN(0001) surfaces using a sputtering method. Amorphous films deposited at room temperature were annealed at a substrate temperature of 500 °C in vacuum to form single-phase anatase films. Films with a thickness of 170 nm exhibited a resistivity of 8×10−4 Ω cm with absorptance less than 5% at a wavelength of 460 nm. Furthermore, the refractive index of the Nb-doped TiO2 was well matched to that of GaN. These findings indicate that Nb-doped TiO2 is a promising material for use as transparent electrodes in GaN-based light emitting diodes (LEDs), particularly since reflection at the electrode/GaN boundary can be suppressed, enhancing the external quantum efficiency of blue LEDs.

Blue, green, and red micro‐light‐emitting diodes (LEDs) have been expected to serve as light sources for next‐generation full‐color displays. This study fabricated an InGaN LED with an active layer comprising stacked red, green, and blue active layers separated by interlayers using the metal‐organic vapor‐phase epitaxy method for application to a monolithic full‐color LED. Experimental results and band simulations revealed that the emission wavelength during current injection was controllable via adjustments to the Si doping amount of the interlayer. For an Si doping amount of the interlayer of approximately 2×1018 cm‐3, only the red active layer closest to the p‐side emitted light with a wavelength of ∽610 nm. With decrease in the Si doping amount in the interlayer, the emission intensity from the n‐side active layer, that is, the green and blue active layers, increased. Moreover, the Si‐doped interlayer acted as a barrier against holes diffusing from the p‐side to the n‐side, thus controlling the amount of carrier injected into each active layer. Additionally, the green and blue active layers under the red active layer improved the emission characteristics of the red active layer. These results indicate the importance of this technology for realizing monolithic, full‐color InGaN‐based LEDs.This article is protected by copyright. All rights reserved.