2H to 1T phase based transition metal dichalcogenide sensor for optical and electronic detection of strong electron donor chemical vapors
Inventors
Friedman, Adam L. • Perkins, F. Keith • Culbertson, James C. • Hanbicki, Aubrey T. • Campbell, Paul M.
Assignees
Publication Number
US-11841338-B2
Publication Date
2023-12-12
Expiration Date
2036-07-19
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Abstract
Optical and electronic detection of chemicals, and particularly strong electron-donors, by 2H to 1T phase-based transition metal dichalcogenide (TMD) films, detection apparatus incorporating the TMD films, methods for forming the detection apparatus, and detection systems and methods based on the TMD films are provided. The detection apparatus includes a 2H phase TMD film that transitions to the 1T phase under exposure to strong electron donors. After exposure, the phase state can be determined to assess whether all or a portion of the TMD has undergone a transition from the 2H phase to the 1T phase. Following detection, TMD films in the 1T phase can be converted back to the 2H phase, resulting in a reusable chemical sensor that is selective for strong electron donors.
Core Innovation
The invention provides sensors incorporating transition metal dichalcogenide (TMD) films that undergo a phase change from a semiconducting 2H trigonal prismatic phase to a metallic 1T octahedral phase upon exposure to strong electron-donor chemical vapors. Detection apparatus, methods for forming these apparatus, and systems based on these TMD films are also provided. The phase state of the TMD film is determined after exposure to an unknown chemical vapor to assess whether the film has transitioned from the 2H phase to the 1T phase, indicating the presence of a strong electron donor.
A problem addressed by the invention is the need for chemical vapor sensors that combine high sensitivity and high selectivity for strong electron donors, while providing inherent mechanical flexibility, low power consumption, rapid response, and reusability. Existing sensors often lack selectivity, respond to water vapor complicating usage, require different sensor types for each analyte, have temperature and humidity dependencies, require significant power, or have slow response and refresh rates. There is also a challenge in differentiating between the 2H and 1T phases of TMD films, as well as limitations with existing detection technologies such as IMS and mass spectrometers in terms of size, power, resolution, and sensitivity.
The invention leverages the reversible 2H to 1T phase transition in TMD thin films caused by excess charge from strong electron donor analytes to create reusable chemical sensors that selectively detect such analytes. The phase change results in measurable changes in conductance and optical properties, such as photoluminescence quenching and the appearance of characteristic Raman peaks (J1, J2, and J3). The sensors can be engineered with metallic 1T contact regions and semiconducting 2H channel regions to enhance selectivity and signal-to-noise ratio by eliminating Schottky barriers at contacts. After detection, the 1T phase films can be converted back to the 2H phase, making the sensors reusable.
Claims Coverage
The claims include one independent claim describing a sensor device comprising specific TMD film phases and electrical contacts. The inventive features relate to the sensor structure and its phase-engineered regions.
Sensor with phase-engineered TMD thin film regions and electrically-conductive leads
The sensor includes a substrate with a transition metal dichalcogenide thin film comprising at least one first region having a 2H phase, and at least two second regions having a 1T phase that are directly in contact with at least two electrically-conductive leads.
The claims primarily cover a sensor device comprising a TMD thin film on a substrate with defined 2H and 1T phase regions, where the 1T phase regions contact electrically-conductive leads. The claims focus on the sensor structure that enables detection of strong electron donors through phase state distinctions.
Stated Advantages
The sensors provide high sensitivity and high selectivity for strong electron donor chemical vapors.
The sensors are mechanically flexible, have low power consumption, and can be fabricated inexpensively.
They have rapid response times, with fast sensing possible in about 2 seconds or faster.
The sensors are reusable by converting the TMD film back from the 1T phase to the 2H phase via annealing.
The sensor design eliminates Schottky barriers, improving selectivity and signal-to-noise ratio.
The sensors exhibit minimal interference from water vapor and function over wide environmental conditions.
Documented Applications
Detection of toxic industrial chemicals (TICs), chemical warfare agents (CWAs), and explosive chemicals that are strong electron donors.
Use as chemical vapor sensors integrated into clothing, gas masks, vehicles, and portable detection systems for industrial, security, and military applications.
Active electronic sensing systems monitoring conductance changes and passive optical sensing systems monitoring photoluminescence and Raman signals for chemical vapor detection.
Integration into wearable or portable devices communicating detection information wirelessly to users or centralized controllers.
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