Efficient Electrochemical Potentiostatic Activation Method for GaN-Based Green Vertical-LEDs

Abstract

An efficient electrochemical potentiostatic activation (EPA) method was designed and performed for hydrogen atoms removal from inside a Mg-doped gallium nitride (GaN) layer of green vertical light-emitting diodes (V-LEDs). The EPA method was conducted at the potentiostatic conditions of 2, 3, and 5 V for 5 mins. The role of the applied voltage value in the breaking of the Mg-H complexes and in increasing the holes concentration inside the p-GaN layer in terms of LED device performances was investigated. The internal quantum efficiency (IQE) of the green V-LEDs behaved inversely with the applied voltage. The IQE of green V-LEDs EPA processed with a low voltage of 2 V realized an improvement of about 6% and only about 2.5% for green V-LEDs EPA processed with a high voltage of 5 V at an injection current of 100 mA compared to the conventional rapid thermal annealing method. The light output power achieved the highest enhancement of about 10.5% at 100 mA when applying the lowest voltage of 2 V, which originated from an improvement of the IQE. The forward voltage was also reduced after the EPA process. The developed EPA method was proven to effectively improve the external quantum efficiency of green V-LEDs.

Optimized Aluminum Reflector for Enhancement of UVC Cathodoluminescence Based-AlGaN Materials with Carbon Nanotube Field Emitters

“…One of the issues concerns the deepening of the Mg-acceptor level, which would make it difficult to deposit the high-conductivity p-type layer [ 7 , 8 , 9 , 10 ]. In addition, the poor structural quality of the AlGaN epitaxial layers would cause dislocations and create non-radiative defects that destroy the internal quantum efficiency of the LEDs [ 11 , 12 , 13 , 14 , 15 ]. Furthermore, these devices currently display low light extraction efficiency and output power [ 16 , 17 , 18 , 19 ].…”

Electrochemical Potentiostatic Activation for the Improvement of 270 nm AlGaN-Based UV-C Light-Emitting Diodes

“…We have demonstrated and suggested in previous reports that electrochemical potentiostatic activation (EPA) treatment is effective in improving the hole carrier concentration in p-type GaN-based LEDs. [14][15][16][17][18] The neutral Mg-H bond is broken down into Mg − and H + by chemical solvent in the EPA method under constant voltage; this mechanism eventually leads to various effects, such as increased internal quantum efficiency (IQE), an improved the leakage current value in the reverse current region, and an extended lifetime of LEDs.…”