Unveiling and eliminating the parasitic hole loss in AlGaN-based deep-ultraviolet light-emitting diodes

The parasitic hole loss during injection is experimentally unveiled in AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs), which is attributed to electron accumulation at the interface of active region and electron blocking layer. It is demonstrated that the loss arises mainly through the non-radiative recombination process, making it unnoticeable under normal operating conditions, e.g., at room temperature. A strategy of DUV-LEDs featuring the active region ending with a well layer is accordingly proposed to propel electron accumulation into the last quantum well. As a consequence, holes can be effectively injected into the wells without parasitic loss, where efficient radiative recombination for deep-ultraviolet emission occurs as hoped. The light output power is then enhanced by 23% at 100 mA in 277 nm DUV-LEDs. Meanwhile, the maximum wall-plug efficiency reaches 9.98% at 10 mA. The strategy in this study is compatible with the present commercial DUV-LED epitaxial structure, enabling it to promote further development of this field.