Size-Independent Forward Voltage Micro-LED with an Epitaxial Junction

Conventional tunnel junction micro-LEDs currently face challenges of higher voltage penalties and varied voltage with different device sizes. Unfortunately, size-dependent voltage characteristics limit the applications of micro-LEDs and result in a lack of device reliability. Thus, overcoming the size dependence of the forward voltage in tunnel junction micro-LEDs would increase their potential to meet the demands of next-generation display applications. 

Researchers at the University of California, Santa Barbara have fabricated size-independent low forward voltage micro-LEDs with an epitaxial tunnel junction (TJ) comprised of p+GaN and n+GaN layers. Utilizing selective area growth (SAG) for regular and micro-size InGaN LEDs, the optimized devices exhibit a very small voltage penalty of 0.2-0.3 V compared to conventional indium tin oxide contact LEDs. Therefore, this composition solves the issue of forward voltage variation in different size tunnel junction micro-LEDs by realizing a size-independent low forward voltage device.