High‐Performance, Transparent Thin Film Hydrogen Gas Sensor Using 2D Electron Gas at Interface of Oxide Thin Film Heterostructure Grown by Atomic Layer Deposition

• Published in: Advanced functional materials Vol. 29; no. 7
• Main Authors: Kim, Sung Min, Kim, Hye Ju, Jung, Hae Jun, Park, Ji‐Yong, Seok, Tae Jun, Choa, Yong‐Ho, Park, Tae Joo, Lee, Sang Woon
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 14-02-2019
• Subjects: Aluminum oxide; atomic layer deposition; Atomic layer epitaxy; Electron density; Electron gas; Epitaxial growth; Film thickness; gas sensor; Gas sensors; Heterostructures; hydrogen; Materials science; Nanoparticles; oxide heterostructure; Palladium; Photovoltaic cells; Response time; Sensors; Strontium titanates; Substrates; thin film; Thin films; Titanium dioxide; Visible spectrum
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201807760

A high‐performance, transparent, and extremely thin (<15 nm) hydrogen (H2) gas sensor is developed using 2D electron gas (2DEG) at the interface of an Al2O3/TiO2 thin film heterostructure grown by atomic layer deposition (ALD), without using an epitaxial layer or a single crystalline substrate. Palladium nanoparticles (≈2 nm in thickness) are used on the surface of the Al2O3/TiO2 thin film heterostructure to detect H2. This extremely thin gas sensor can be fabricated on general substrates such as a quartz, enabling its practical application. Interestingly, the electron density of the Al2O3/TiO2 thin film heterostructure can be tailored using ALD process temperature in contrast to 2DEG at the epitaxial interfaces of the oxide heterostructures such as LaAlO3/SrTiO3. This tunability provides the optimal electron density for H2 detection. The Pd/Al2O3/TiO2 sensor detects H2 gas quickly with a short response time of <30 s at 300 K which outperforms conventional H2 gas sensors, indicating that heating modules are not required for the rapid detection of H2. A wide bandgap (>3.2 eV) with the extremely thin film thickness allows for a transparent sensor (transmittance of 83% in the visible spectrum) and this fabrication scheme enables the development of flexible gas sensors.
A high‐performance, transparent, and extremely thin (≈15 nm) hydrogen (H2) gas sensor is developed using 2D electron gas at the interface of an Al2O3/TiO2 thin film heterostructure. This extremely thin gas sensor can be fabricated on general substrates such as a glass using atomic layer deposition, and this fabrication scheme enables the development of flexible gas sensors.