Effect of Parabolic Quantum Well on Internal Quantum Efficiency of InGaN/GaN based Micro-LED at low current density

Abstract

The quantum cascade stark effect (QCSE) in rectangular shaped quantum well (QW) poses a hindrance to increase the internal quantum efficiency (IQE) of nitride based LEDs. To circumvent the said problem for micro-LEDs operating at low current density, a parabolic QW structure has been proposed which is found to be useful to alleviate the QCSE and to increase the IQE. To emit around 500 nm, it has been observed that use of parabolic QW(instead of rectangular QWs) in the active region of micro-LED results in 10% less applied voltage to reach 0.1 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> current at which ~50% more IQE is obtained. Further a variation in the number of parabolic QWs indicates that a two quantum well structure in the active region of the designed micro-LED will result in maximum IQE at a low current density of 0.1 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . However, the performance of the parabolic QWs are inferior to the rectangular QWs at high current densities where the conventional LED works.