IR hot carrier based photodetection in titanium nitride oxide thin film-Si junctions
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MRS Advances © 2020 Materials Research Society DOI: 10.1557/adv.2020.129
IR hot carrier based photodetection in titanium nitride oxide thin film-Si junctions Nicholas A. Güsken1,*, Alberto Lauri1, Yi Li1,3, Andrea Jacassi,1 Takayuki Matsui1, Brock Doiron1, Ryan Bower2, Anna Regoutz2, Andrei Mihai2, Peter K. Petrov2, Rupert F. Oulton1, Lesley F. Cohen1, Stefan A. Maier1,3 1
The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ, United Kingdom 2
Department of Materials, Imperial College London, London SW7 2AZ, United Kingdom
3 Chair in Hybrid Nanosystems, Nanoinstitute Munich, Fakultät für Physik, Ludwig-Maximilians Universität München, 80539 München, Germany
*Correspondence: [email protected]
ABSTRACT: Hot carrier based methods constitute a valuable approach for efficient and silicon compatible sub-bandgap photodetection. Although, hot electron excitation and transfer have been studied extensively on traditional materials such as Au and Ti, reports on alternative materials such as titanium nitride (TiN) are rare. Here, we perform hot hole photodetection measurements on a p-Si/metal thin film junction using Ti, Au and TiN. This material is of interest as it constitutes a refractory alternative to Au which is an important property for plasmonic applications where high field intensities can occur. In contrast to Au, a TiN/Si junction does not suffer from metal diffusion into the Si, which eases the integration with current Si-fabrication techniques. This work shows that a backside illuminated p-Si/TiN system can be used for efficient hot hole extraction in the IR, allowing for a responsivity of 1 mA/W at an excitation wavelength of 1250 nm and at zero bias. Via a comparison between TiN and other commonly used materials such as Au, the origin of this comparably high photoresponse can be traced back to be directly linked to a thin TiO2-x interfacial layer allowing for a distinct hot-hole transfer mechanism. Moreover, the fabrication of TiN nanodisk arrays is demonstrated which bears great promise to further boost the device efficiency.
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INTRODUCTION: Novel approaches enabling efficient ways to create photo-voltages, range from 2D material plasmonic hybrid structures [1-3] over metal-insulator-metal waveguides [4,5] to semiconductor/metal nanowire junctions [6]. One of the most widely studied systems for hot-carrier based photodetection however, are common semiconductor(SC)/metal junctions. Indeed, this type of hot carrier photo-detection platform has attracted enormous attention mainly due to its capability of creating a photovoltage at a semiconductor/metal junction without being limited by the semiconductor bandgap energy. Additionally, the ability to pattern junctions allowing for plasmonic resonances, enabled a strong effi
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