On-chip nanophotonic broadband wavelength detector with 2D-Electron gas

Vishal Kaushik,Lalit Singh,Mukesh Kumar,Moustafa Ahmed,Yas Al-Hadeethi,Hamed Dalir,Sulabh Srivastav,Volker J Sorger,Swati Rajput,Elham Heidari,Prem Babu

doi:10.1515/nanoph-2021-0365

Abstract

Abstract Miniaturized, low-cost wavelength detectors are gaining enormous interest as we step into the new age of photonics. Incompatibility with integrated circuits or complex fabrication requirement in most of the conventionally used filters necessitates the development of a simple, on-chip platform for easy-to-use wavelength detection system. Also, intensity fluctuations hinder precise, noise free detection of spectral information. Here we propose a novel approach of utilizing wavelength sensitive photocurrent across semiconductor heterojunctions to experimentally validate broadband wavelength detection on an on-chip platform with simple fabrication process. The proposed device utilizes linear frequency response of internal photoemission via 2-D electron gas in a ZnO based heterojunction along with a reference junction for coherent common mode rejection. We report sensitivity of 0.96 μA/nm for a broad wavelength-range of 280 nm from 660 to 940 nm. Simple fabrication process, efficient intensity noise cancelation along with heat resistance and radiation hardness of ZnO makes the proposed platform simple, low-cost and efficient alternative for several applications such as optical spectrometers, sensing, and Internet of Things (IOTs).

Highlights

As electronics-based technologies are reaching their performance bottlenecks, research community is shifting their focus from electrons to photons
Low cost, on-chip wavelength detectors which can be extremely useful in the fields of sensing, Internet of Things (IOTs), communication and environmental monitoring have attracted the attention of the researchers in recent years
Wavelength detection capability of the proposed ZnO based dual heterojunction has been experimentally demonstrated for part-visible part-IR region of spectrum over a broad range of frequencies

Summary

Introduction

As electronics-based technologies are reaching their performance bottlenecks, research community is shifting their focus from electrons to photons. To achieve high spectral resolution it is inevitable to integrate complex geometries with very low fabrication tolerance; broadband operation is achieved by employing multiple layers of different materials This increases the complexity and leads to excessive production costs [14, 15]. Another approach that uses 2D materials is gaining a lot of attention due to their unique opto-electronic properties such as ultrahigh responsivity, fast photoresponse and broad detection range Issues such as lack of maturity in large scale growth of high-quality film along with concerns related with pattering and highly quality Ohmic contacts damages the wide appeal that 2DM enjoy. Bandgap engineering in ZnO based alloy has been used to demonstrate heterojunctions with very high density of 2-DEG confined at the junction barrier. The device is engineered to reduce intensity dependence of the photoemission current via 2-DEG formed at the ZnO based heterojunctions. High density of 2-DEG offers high IQE along with high photocurrent making it a perfect platform for applications in wavelength demodulation, sensing, IOT etc

Device design

Device measurements

Discussion

Conclusion