Dopant concentrations analysis on electro-optic performances of gallium nitride-based ultraviolet light-emitting diode chip

Abstract

A high dopant concentration significantly reduces the peak current of the internal quantum efficiency (IQE) of the light-emitting diode (LED). The effect of the dopant concentration on the epitaxial layer toward the IQE, current density, and IQE droop of gallium nitride (GaN)-based LED chip is analyzed with the doping variation from 1 × 1015 cm-3 to 1 × 1021 cm-3. The required current density for the dopant concentrations of 1 × 1015 cm-3 is 122.42 A / cm-2 with the IQE droop of 10%. Meanwhile, for the dopant concentrations of 1 × 1021 cm-3, the required current density for achieving peak IQE is 0.67 A / cm-2 with an IQE droop of 51%. The increase in dopant concentrations reduces the current density necessary for achieving peak IQE while increasing IQE droop. The optimization is performed for the device performances based on the peak current and IQE droop. The optimal dopant concentration for this GaN-based LED lies between 1 × 1017 cm-3 and 1 × 1018 cm-3, which is 4.47 × 1017 cm-3, with a peak IQE of 69.1%. The proposed epitaxy structure provides the optimal doping concentration for the homojunction LED chip with a compatible activation current. The results achieved in this work may benefit the entire optoelectronics field.