Selectivity and Cross-Sensitivity of Transfer-Free Fabricated Nanocrystalline Graphene Field-Effect Gas Sensors

Abstract

With respect to its high surface-to-volume ratio graphene shows promising properties for electrochemical sensing. By means of resistive measurements, i.e. having the backgate connected to ground, we demonstrate low-level detection of ammonia (1), nitrogen dioxide (calibration gas 1,000ppm) and carbon monoxide (calibration gas 1,000ppm) under vacuum pressures ranging from 2·10-4 mbar to 4·10-3 mbar using our transfer-free fabricated nanocrystalline graphene field-effect transistors (ncGFETs). A change in conductivity can be observed for all three gases. However, no selectivity between the gases is yet achieved. Therefore, by analyzing the ncGFET input characteristics a mechanism to discriminate between different gaseous species is developed based on the shift of the charge neutrality point (CNP) (2) as well as on the evolution of the hysteresis loop present in our ncGFETs.