Size-Dependent Quantum Efficiency of Flip-Chip Light-Emitting Diodes at High Current Injection Conditions

Versatile applications call for InGaN-based light-emitting diodes (LEDs) to operate at ultra-high current densities with high quantum efficiency. In this work, we investigated the size-dependent effects of the electrical and optical performance of LEDs as increasing the current density up to 100 A/cm2, which demonstrated that mini-strip flip-chip LEDs were superior option to achieve better performance. In detail, at a current density of 100 A/cm2, the light output power density of these mini-strip LEDs was improved by about 6.1 W/cm2, leading to an improvement in the wall-plug efficiency by 4.23%, while the operating temperature was reduced by 11.3 °C, as compared with the large-sized LEDs. This could be attributed to the increase in the sidewall light extraction, alleviated current crowding effect, and improved heat dissipation. This work suggests an array of mini-strip LEDs would provide an option in achieving higher luminescent efficiency at ultrahigh current injection conditions for various applications.