Wavelength-Tunable Green Light Sources Based on ZnO:Ga Nanowire/p-InGaN Heterojunctions

InGaN-based materials and structures have attracted extensive attention in developing green light-emitting diodes (LEDs), but the fabrication of high-performance low-dimensional green LEDs is seriously limited to the sample preparation, device construction, green gap, and efficiency droop. In this work, a kind of green LED composed of p-type InGaN layers and a one-dimensional wired ZnO via Ga incorporation, featuring a green wavelength of 520.0 nm and a linewidth of about 34.0 nm, was designed. The LED characteristics, with respect to the peak wavelengths and linewidths, are almost constant at different input currents, indicating the insensibility to the quantum-confined Stark effect commonly observed in InGaN-based light sources. The color coordinate is really close to pure green (0.170, 0.797) of the Rec. 2020 standard. Significantly, the efficiency droop in the fabricated LED is temperate, suggesting that the recombination of carriers can occur toward the n-ZnO:Ga/p-InGaN interface instead of the p-InGaN region. With an increase in Ga-doping concentration in ZnO:Ga wires, the main EL peaks show a significant red shift from 520 to 584 nm in the green and yellow emission spectrum. This wavelength-tuning is further confirmed by the successfully varied color coordinates. The fabrication of one-dimensional wired green LEDs not only can break through the green gap but also can work as a potential candidate to developing solid-state lighting in the visible band for a wide range of practical applications.