Van der Waals Integrated Silicon/Graphene/AlGaN Based Vertical Heterostructured Hot Electron Light Emitting Diodes.

Nallappagari Krishnamurthy Manjunath,Yanghua Lu,Chang Liu,Xutao Yu,Shisheng Lin

doi:10.3390/nano10122568

Nallappagari Krishnamurthy Manjunath, Yanghua Lu + Show 3 more

Open Access

https://doi.org/10.3390/nano10122568

Copy DOI

Journal: Nanomaterials	Publication Date: Dec 21, 2020
Citations: 1	License type: CC BY 4.0

Affiliation: Zhejiang University

Abstract

Silicon-based light emitting diodes (LED) are indispensable elements for the rapidly growing field of silicon compatible photonic integration platforms. In the present study, graphene has been utilized as an interfacial layer to realize a unique illumination mechanism for the silicon-based LEDs. We designed a Si/thick dielectric layer/graphene/AlGaN heterostructured LED via the van der Waals integration method. In forward bias, the Si/thick dielectric (HfO2-50 nm or SiO2-90 nm) heterostructure accumulates numerous hot electrons at the interface. At sufficient operational voltages, the hot electrons from the interface of the Si/dielectric can cross the thick dielectric barrier via the electron-impact ionization mechanism, which results in the emission of more electrons that can be injected into graphene. The injected hot electrons in graphene can ignite the multiplication exciton effect, and the created electrons can transfer into p-type AlGaN and recombine with holes resulting a broadband yellow-color electroluminescence (EL) with a center peak at 580 nm. In comparison, the n-Si/thick dielectric/p-AlGaN LED without graphene result in a negligible blue color EL at 430 nm in forward bias. This work demonstrates the key role of graphene as a hot electron active layer that enables the intense EL from silicon-based compound semiconductor LEDs. Such a simple LED structure may find applications in silicon compatible electronics and optoelectronics.

Highlights

Light-emitting diodes (LEDs) are widely adopted electrically generated light emitting sources and possess vital applications in modern society, III–V based compound semiconductors (GaN, AlGaN, etc.), which are the most commercialized materials for the realization of efficient light emitting diodes (LED) [1,2,3,4]
We have demonstrated the possibility of high intense LEDs by combining Si, double-layer graphene (DLG), and p-type AlGaN [10,11,12]
In forward applied bias voltages, the silicon/dielectric layer (HfO2, SiO2) heterostructure accumulates numerous hot electrons at the interface of the Si/dielectric layer, and these electrically induced hot electrons are capable of crossing the thick dielectric barrier via electron-impact ionization mechanism and can be injected into the graphene

Summary

Introduction

Light-emitting diodes (LEDs) are widely adopted electrically generated light emitting sources and possess vital applications in modern society, III–V based compound semiconductors (GaN, AlGaN, etc.), which are the most commercialized materials for the realization of efficient LEDs [1,2,3,4]. The double-layer graphene (DLG) is considered to be a better candidate over the monolayer as a substrate and a conductive electrode in device fabrication because DLG possesses better mechanical properties, which can avoid the misconceptions caused by damage or discontinuity in monolayer graphene [18]. We have presumed DLG as an interfacial layer in between the Si/dielectric layer and p-AlGaN layer to realize a unique illumination mechanism for better performance of LEDs. Recently, the twisted double-layer graphene (DLG) has been demonstrated to be superconducting at low temperatures [19]. As graphene has a zero band gap, the hot electron can experience multi electron-electron interaction before cooling in the time scale of several tens or hundreds of fs, which results in the effect of carriers multiplication (CM) been proven by many reports [20,21]

Methods

Results

Conclusion