Intrinsic hydrogen-terminated diamond as ion-sensitive field effect transistor

Ion-sensitive field-effect transistors (ISFET) are fabricated using intrinsic hydrogen-terminated mono-crystalline diamond films. Transistor properties are realized by a surface conductive channel on hydrogen-terminated diamond. The gating is realized by immersing the diamond surface into electrolyte solution which is contacted by a platinum electrode. Hydrogen termination of diamond surface acts as a gate insulation without any additional oxide layer. The response of gate potential to pH is about −56−56  mV/pH. The results are discussed in terms of transfer doping mechanism, Nernst equation, and electrochemical properties of diamond surfaces. They are also compared with ISFETs which employ ion-sensitive gate oxides.