Researchers from the University of Osaka and Ritsumeikan University have demonstrated a terbium-doped AlGaN-based LED for the first time. This is exciting as terbium-doped AlGaN can be used to create LEDs that emits red, green and blue colors, which means that a microLED display can use the same material platform with full RGB emission.
The researcher began the process by forming AlGaN-on-sapphire heterostructure in a Taiyo Nippon Sanso SR-200 MOCVD reactor. Devices were fabricated with terbium-doped layers with AlGaN compositions of Al0.36Ga0.64N, Al0.53Ga0.47N, Al0.59Ga0.41N and Al0.62Ga0.38N. This process is scalable to mass production, no more challenging than standard LEDs.
The researchers say that the EQE of these microLEDs emitters increases with aluminium concentration: it is just over 10 times higher for Al0.62Ga0.38N than Al0.36Ga0.64N. While an increase in aluminium concentration degrades the electrical properties, Tb3+ emission is much stronger, due to enhanced energy transfer from the alloy to the dopant. These LEDs produce incredibly stable electroluminescent emission peaks at around 620 nm, 580 nm, 550 nm and 490 nm, due to 5D4 – 7FJ (J = 3,4,5,6) transitions.
With the addition of the terbium dopant, AlGaN LEDs produce sharp electroluminescent peaks at around 620 nm, 580 nm, 550 nm and 490 nm.
