Overshoot effects of electron on efficiency droop in InGaN/GaN MQW light-emitting diodes

Yang Huang,Xiaoyan Yi,Yao Guo,Guohong Wang,Guodong Yuan,Jinmin Li,Zhiqiang Liu,Junxi Wang,Shaoteng Wu

doi:10.1063/1.4948511

Abstract

To evaluate electron leakage in InGaN/GaN multiple quantum well (MQW) light emitting diodes (LEDs), analytic models of ballistic and quasi-ballistic transport are developed. With this model, the impact of critical variables effecting electron leakage, including the electron blocking layer (EBL), structure of multiple quantum wells (MQWs), polarization field, and temperature are explored. The simulated results based on this model shed light on previously reported experimental observations and provide basic criteria for suppressing electron leakage, advancing the design of InGaN/GaN LEDs.

Highlights

The origin of efficiency droop in InGaN/GaN light emitting diodes (LEDs) remains a topic of active debate.[1,2] many theories have attempted to explain these experimental observations, including device heating,[3] delocalization of carriers,[4] Auger recombination,[5] and electron leakage,[6] there is still no consensus on their underlying physical mechanism
The simulated results based on this model shed light on previously reported experimental observations and provide basic criteria for suppressing electron leakage, advancing the design of InGaN/GaN LEDs
Ballistic transport in more complex and significant multiple quantum well (MQW) structures which are widely used in InGaN/GaN LEDs, has yet to be studied

Summary

INTRODUCTION

The origin of efficiency droop in InGaN/GaN light emitting diodes (LEDs) remains a topic of active debate.[1,2] many theories have attempted to explain these experimental observations, including device heating,[3] delocalization of carriers,[4] Auger recombination,[5] and electron leakage,[6] there is still no consensus on their underlying physical mechanism. Electron leakage is commonly regarded as having an important contribution to the remarkable efficiency loss, especially at high injected current Such leakage is caused by poor hole-injection efficiency,[6] an ineffective electron blocking layer (EBL),[7,8] non-capture of electrons by quantum wells (QWs),[9] and electron escape from the QWs.[10] Recently, ballistic and quasi-ballistic transport in electron leakage was investigated for InGaN/GaN LEDs with single double heterostructure (DH) active regions, producing a good agreement with experiments.[11,12] Ballistic transport in more complex and significant multiple quantum well (MQW) structures which are widely used in InGaN/GaN LEDs, has yet to be studied.

Lb exp exp

DISCUSSION

CONCLUSIONS