Optimizing hot electron harvesting at planar metal–semiconductor interfaces with titanium oxynitride thin films
File(s)
Supporting information
Accepted version
Author(s)
Type
Journal Article
Abstract
Understanding metal-semiconductor interfaces is critical to the advancement of photocatalysis and sub-bandgap solar energy harvesting where electrons in the metal can be excited by sub-bandgap photons and extracted into the semiconductor. In this work, we compare the electron extraction efficiency across Au/TiO2 and titanium oxynitride (TiON)/TiO2-x interfaces, where in the latter case the spontaneously forming oxide layer (TiO2-x) creates a metal-semiconductor contact. Time-resolved pump-probe spectroscopy is used to study the electron recombination rates in both cases. Unlike the nanosecond recombination lifetimes in Au/TiO2, we find a bottleneck in the electron relaxation in the TiON system, which we explain using a trap-mediated recombination model. Using this model, we investigate the tunability of the relaxation dynamics with oxygen content in the parent film. The optimized film (TiO0.5N0.5) exhibits the highest carrier extraction efficiency (NFC ≈ 2.8 × 1019 m-3), slowest trapping, and an appreciable hot electron population reaching the surface oxide (NHE ≈ 1.6 × 1018 m-3). Our results demonstrate the productive role oxygen can play in enhancing electron harvesting and prolonging electron lifetimes, providing an optimized metal-semiconductor interface using only the native oxide of titanium oxynitride.
Date Issued
2023-06-12
Date Acceptance
2023-05-23
Citation
ACS Applied Materials and Interfaces, 2023, 25 (15), pp.30417-30426
ISSN
1944-8244
Publisher
American Chemical Society
Start Page
30417
End Page
30426
Journal / Book Title
ACS Applied Materials and Interfaces
Volume
25
Issue
15
Copyright Statement
Copyright © 2023 The Authors. Published by American Chemical Society. This work is published under a CC BY licence.
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/37307410
Subjects
electron lifetimes
hot electrons
photocatalysis
plasmonics
pump−probe spectroscopy
Publication Status
Published
Coverage Spatial
United States
Date Publish Online
2023-07-12