Molecular bridge-mediated ultralow-power gas sensing
Abstract
We report the electrical detection of captured gases through measurement of the quantum tunneling characteristics of gas-mediated molecular junctions formed across nanogaps. The gas-sensing nanogap device consists of a pair of vertically stacked gold electrodes separated by an insulating 6 nm spacer (~1.5 nm of sputtered α-Si and ~4.5 nm ALD SiO2), which is notched ~10 nm into the stack between the gold electrodes. The exposed gold surface is functionalized with a self-assembled monolayer (SAM) of conjugated thiol linker molecules. When the device is exposed to a target gas (1,5-diaminopentane), the SAM layer electrostatically captures the target gas molecules, forming a molecular bridge across the nanogap. The gas capture lowers the barrier potential for electron tunneling across the notched edge region, from ~5 eV to ~0.9 eV and establishes additional conducting paths for charge transport between the gold electrodes, leading to a substantial decrease in junction resistance. We demonstrated an output resistance change of >108 times upon exposure to 80 ppm diamine target gas as well as ultralow standby power consumption of <15 pW, confirming electron tunneling through molecular bridges for ultralow-power gas sensing.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 29, 2021
- Source ID
- 10.1038/s41378-021-00252-3
Entities
People
- Aishwaryadev Banerjee
- Ashrafuzzaman Bulbul
- Carlos H. Mastrangelo
- H. Kim
- Kyeong Heon Kim
- R. Looper
- Samuel Broadbent
- Seungbeom Noh
- Shakir-ul Haque Khan
Organizations
- ARPA-E
- United States Department of Defense