Deep levels induced optical memory effect in thin InGaN film

B B Wang,J J Zhu,F Liang,Y Xing,D S Jiang,W Liu,Z S Liu,D G Zhao,P Chen,L Q Zhang,J Yang,M Li,S T Liu

doi:10.1063/1.5045811

Abstract

An optical memory effect is found in a 20 nm InGaN film. With increasing illumination time, photoluminescence (PL) intensity of InGaN rises at first and then falls. We present that this effect is caused by carriers capture in deep levels near interfaces between GaN and InGaN. Firstly, carriers captured by deep levels near the interfaces reduces the band inclination in InGaN. This cause the rise of PL intensity. Secondly, more and more captured carriers may form anti-shielding, which enhances band inclination and results in the decrease of PL intensity. Carriers captured in previous illumination can remain for a long time after illumination is blocked, which make InGaN show an optical memory effect.

Highlights

InGaN materials are widely used as active regions in light emission devices, such as lightemission diodes (LEDs) and laser diodes (LDs).[1,2,3]
In InGaN, PL intensity may rise gradually to the maximum or fall exponentially within tens of seconds of an optical illumination. Such different behaviors of PL variation depends on the InGaN samples are excited by 365 nm or by 405 nm laser.[7]
We propose that optical memory effect is dominated by carrier capture caused by deep levels

Summary

Introduction

InGaN materials are widely used as active regions in light emission devices, such as lightemission diodes (LEDs) and laser diodes (LDs).[1,2,3] due to the lack of a comprehensive understanding of their luminescence properties, some phenomena still cannot be explained very well.[4]. Deep levels induced optical memory effect in thin InGaN film Li5 1Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China 2College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Science, Beijing 100049, China 3School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China 4Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215125, China 5Microsystem & Terahertz Research Center, Chinese Academy of Engineering Physics, Chengdu 610200, China (Received 25 June 2018; accepted 23 August 2018; published online 30 August 2018)

Results

Conclusion