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...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 sputteredα-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.展开更多
基金We would like to acknowledge the contributions of Prattaydeepta Kairy,Chayanjit Ghosh,and Navid Farhoudi for assisting with various aspects of the sensor testing.This work made use of University of Utah USTAR shared facilities supported,in part,by the MRSEC Program of NSF under Award No.DMR-1121252This work was sponsored under cooperative agreement HR0011-15-2-0049 of the DARPA N-ZERO programThis research work was also generously funded by the cooperative agreement of DE-AR0001064 of the ARPAE OPEN 2018 program(Program Manager Dr.David Babson)in the United States.We feel grateful for the generous technical and administrative support from the ARPAE technical support staff(Dr.David Lee and Dr.Mike Xiao-Zhu Fan).
文摘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 sputteredα-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.
