Ultra-stable multiple emission wavelengths produced by Tb-doped Al x Ga1− x N-based light-emitting diodes

Tb-doped semiconductors are candidates for novel full-color light sources in next-generation high-definition displays. Particularly, Tb-doped AlxGa1−xN (AlxGa1−xN:Tb) has attracted much attention because Tb3+ ions doped into AlxGa1−xN show ultra-stable multi-color emissions consisting of blue, green, yellow, and red. Herein, we demonstrate room-temperature operation of AlxGa1−xN:Tb light-emitting diodes (LEDs) under current injections and characterize the optical/electrical properties. Ultra-stable Tb3+ emissions with narrow linewidths are clearly observed, and it is revealed that the quantum efficiencies monotonically increase for Al-richer conditions. Furthermore, the LEDs fabricated on AlN templates show superior optical and electrical properties to those on GaN templates because Al-rich AlxGa1−xN:Tb layers are coherently grown on the AlN templates due to the decreased lattice mismatch, resulting in higher crystal quality and shortening the radiative lifetime (from 280 to 227 μs) related to 5D4–7FJ (J = 3, 4, 5, 6) transitions in Tb3+ ions. Through color filters, RGB emissions originating from the respective transitions are selectively obtained at the same light-emitting area. The multi-color AlxGa1−xN:Tb-based LEDs would be a novel light source for wide applications such as micro-LED displays.