Superfluorescence of Sub-Band States in C-Plane In0.1Ga0.9N/GaN Multiple-QWs.

Cairong Ding,Xueran Zeng,Zesheng Lv,Baijun Zhang

doi:10.3390/nano12030327

Abstract

Superfluorescence is a collective emission from quantum coherent emitters due to quantum fluctuations. This is characterized by the existence of the delay time ( for the emitters coupling and phase-synchronizing to each other spontaneously. Here we report the observation of superfluorescence in c-plane In0.1Ga0.9N/GaN multiple-quantum wells by time-integrated and time-resolved photoluminescence spectroscopy under higher excitation fluences of the 267 nm laser and at room temperature, showing a characteristic from 79 ps to 62 ps and the ultrafast radiative decay (7.5 ps) after a burst of photons. Time-resolved traces present a small quantum oscillation from coupled In0.1Ga0.9N/GaN multiple-quantum wells. The superfluorescence is attributed to the radiative recombination of coherent emitters distributing on strongly localized subband states, Ee1→Ehh1 or Ee1→Elh1 in 3nm width multiple-quantum wells. Our work paves the way for deepening the understanding of the emission mechanism in the In0.1Ga0.9N/GaN quantum well at a higher injected carrier density.

Highlights

Spontaneous emissions (SEs) of photons occur because of coupling between excited two-level systems and vacuum modes of the electromagnetic field, such as the process of fluorescence that is commonly used in displays and lighting—effectively stimulated by its zero-point fluctuations
C-plane InGaN/GaN quantum wells (QWs) as the prevailing active layer have been studied extensively due to their promising applications in group-III nitride semiconductor optoelectronic devices [1,2,3,4]
InGaN/GaN MQWs schematized in Figure 1a were grown on (0001) c-plane sapphire substrates in a metal organic chemical vapor deposition (MOCVD) system with the Thomas

Summary

Introduction

Spontaneous emissions (SEs) of photons occur because of coupling between excited two-level systems and vacuum modes of the electromagnetic field, such as the process of fluorescence that is commonly used in displays and lighting—effectively stimulated by its zero-point fluctuations. Accepted explanations for emission features are the spatial localization of carriers due to random alloy fluctuations, indium compositional fluctuations and well width fluctuations [5,6,7,8,9,10,11,12,13,14,15,16,17,18], the quantum-confined Stark effect (QCSE) because it spatially separates electron and hole wave functions and reduces the wave function overlap in the QWs [19,20,21,22,23,24,25] and the screening of the QCSE under a high excitation that affects the excitation density-dependent emission energy of InGaN/GaN.

Methods

Results

Conclusion