Correlation of spatial electroluminescence inhomogeneity and leakage current behavior of blue and green micro light-emitting diodes

Abstract

Spatially resolved electroluminescence is investigated for InGaN-based blue and green micro-sized light-emitting diodes (μLEDs) to correlate nanoscale emission and macroscopic electrical characteristics using a confocal scanning electroluminescence optical microscopy. It was revealed that more observable emission wavelength inhomogeneity of green μLED can be beneficial for relatively lower leakage current, compared to blue counterpart, in terms of less severe lateral diffusion of injected carriers by highly indium concentrated regions and corresponding suppressed non-radiative recombination at the sidewall defects. This finding was further confirmed by relatively lower tunneling leakage current (ideality factor, n > 2) under low voltage regime (∼2 V) of green μLED and less shifted emission wavelength even at high current densities (>10 A/cm2). Therefore, this systematic comparative analysis of blue and green μLEDs based on their nanoscale electroluminescence and leakage current characteristics enables us to identify the origin of suppressed leakage current from green μLED, which also offers a useful method to characterize μLED for display applications.