Analysis of size dependence and the behavior under ultrahigh current density injection condition of GaN-based Micro-LEDs with pixel size down to 3 μm

In this paper, the GaN-based green micro light-emitting diodes (Micro-LEDs) with various sizes (from 3 to 100 mu m) were fabricated and electro-optically characterized. Atom layer deposition (ALD) passivation and potassium hydroxide (KOH) treatment were applied to eliminate the sidewall damage. The size dependence of Micro-LED was systematically analyzed with current-versus-voltage and current density-versus-voltage relationship. According to the favorable ideality factor results (<1.5), the optimized sidewall treatment was achieved when the device size shrank down to mu m. In addition, the external quantum efficiency (EQE) droop phenomenon, luminance and output power density characteristics were depicted up to the highest current density injection condition to date (120 kA cm(-2)), and 6 mu m device exhibited an improved EQE performance with the peak EQE value of 16.59% at 20 A cm(-2) and over 600k and 6M cd cm(-2) at 1 and 10 A cm(-2), indicating a greater brightness quality for over 3000 PPI multiple display application. Lastly, the blue shift of 6 mu m device with elevating current density was observed in electroluminescence spectra and converted to CIE 1931 color space. The whole shifting track and color variation from 1 A cm(-2) to 120 kA cm(-2) were demonstrated by color coordinates.