Modeling polarization effects on internal quantum efficiency of micro-LEDs at low current density

Abstract

This study investigates the optoelectronic properties of blue micro-light-emitting diodes (µ-LEDs) by modeling the semipolar single quantum well (QW) at low current density. Through simulation analyses, the influences of the eight selected crystal orientations and different QW thicknesses on the internal quantum efficiency (IQE) and forward voltage are investigated for low current density LEDs. The simulation results of the energy band diagram show that reversed polarization increases the band tilt in the same direction as the built-in electric field, resulting in IQE poorer than that of LEDs whose polarization is of the same magnitude but positive. However, reversed polarization also reduces the hole barrier height, resulting in lower forward voltage at the same current density. Finally, it is found that weakly positive-polarized (101̄2) LEDs have the highest IQE and maximum allowed thickness at low current density, which is due to the flat energy band with a reduced band tilt caused by weakly positive polarization.