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.

我们通过测量跨越纳米间隙形成的气体介导分子结的量子隧道特性来报告捕获气体的电检测。气敏纳米间隙器件由一对垂直堆叠的金电极组成，这些电极由绝缘的 6 nm 间隔物（~1.5 nm 的溅射 α-Si 和~4.5 nm ALD SiO ₂)，它在金电极之间的堆叠中被切入约 10 nm。暴露的金表面被共轭硫醇连接分子的自组装单层 (SAM) 功能化。当设备暴露于目标气体（1,5-二氨基戊烷）时，SAM 层会静电捕获目标气体分子，在纳米间隙上形成分子桥。气体捕获降低了穿过缺口边缘区域的电子隧穿势垒，从~5 eV 到~0.9 eV，并为金电极之间的电荷传输建立了额外的导电路径，从而导致结电阻的显着降低。我们展示了 >10 ⁸的输出电阻变化 暴露于 80 ppm 二胺目标气体的时间以及 <15 pW 的超低待机功耗，证实了通过分子桥的电子隧穿用于超低功耗气体传感。