Influence of Undoped‐AlGaN Final Barrier of MQWs on the Performance of Lateral‐Type UVB LEDs

Aluminium gallium nitride (AlGaN)‐based ultraviolet‐B light‐emitting diodes (UVB LEDs) are expected to offer smart size, wider choice of UVB light emission in the wavelengths range of 280 nm > λ > 320 nm, and low cost as well as low power consumption compared with other UV light sources including toxic mercury UV‐lamps. The hole‐tunneling from p‐AlGaN side of UVB LED into the multi‐quantum‐wells (MQWs) is strongly dependent on the thickness (TFB) and Al‐contents of undoped (ud)‐AlGaN final barrier (FB). Herein, the photoluminescence (PL) efficiency from MQWs of the UVB LED devices is investigated and compared with the electroluminescence (EL) spectra as a function of TFB. Subsequently, the dependence of PL efficiency, external quantum efficiency (EQE), and light output power on the TFB of UVB LEDs is attempted, using the same growth condition for all samples except variation in TFB. When TFB is set to 6–7 nm, improvements in the EQE and light output power, respectively, from 4.3% and 7 mW to the high values of 5.6% and 17 mW in emission band of 295–300 nm under continuous‐wave (cw) at room temperature (RT) are achieved. 17 mW semiconducting AlGaN‐based ultraviolet‐B (UVB) light‐emitting diodes (LEDs) at 300 nm emission grown on AlN template are expected to be useful for the production of vitamin D3 in the human body as well as for killing of tomato mosaic virus (ToMV) in tomato. The UV‐light power is improved in AlGaN UVB LEDs using an optimized undoped‐AlGaN final barrier of the quantum well.