Electron-interfered field-effect transistors as a sensing platform for detecting a delicate surface chemical reaction

Abstract

We introduce a new electron-interfered field-effect transistor (EIFET) device with a modified organic charge-modulated FET (OCMFET) structure and demonstrate its ability to detect the surface chemical reaction degree (or rate). When the electrodes used as the control gate (G) and floating G in the OCMFET were changed to the sensing area and voltage-applied electrode, respectively, the threshold voltage (V_th) of the EIFET varies sensitively with the progression of the surface reaction on the control G. Here, the control G is newly referred to as the interference electrode (IE). The results indicate that variations in dV_th/dt in the EIFET coincide almost exactly with the variations in its surface energy (γ_s) after dropping thiol solutions onto the IE, as the model reactive materials are capable of surface reaction with a novel metal. We argue that the surface reaction of IE with TP molecules induces variations in V_ths and suggest that this phenomenon occurs because some of the electrons released during the reaction process accumulate inside the IE and interfere with the primary V_G, thereby partially canceling the applied V_G. Although this study is somewhat lacking in terms of analysis and interpretation, it demonstrates the potential of our newly designed EIFET device to quantify surface chemical reactions.