Ultrathin gate-contacts for metal-semiconductor field-effect transistor devices: An alternative approach in transparent electronics.

Transparent metal-insulator-semiconductor field-effect transistors (TMISFETs) are commonly designated as one keystone of transparent circuitry. TMISFETs were demonstrated using carbon nanotubes, organics, or oxides. The optimization of their gate-insulator as well as the field-effect mobility and switching voltages is of major interest in this research field. We present an alternative approach based on metal-semiconductor field-effect transistors (MESFETs) circumventing these problems of TMISFET technology. We use ultrathin transparent rectifying contacts (TRCs) consisting of non-insulating Ag_xO or Pt_xO layers and a highly conducting capping layer realized by room-temperature sputtering. The process is compatible with other low-temperature, low-cost manufacturing steps. We demonstrate the potential of such TRCs for ZnO-based MESFETs having a transparency of 70% in the visible, on/off-ratios higher than 10⁶ within a gate-voltage sweep of only 2.7 V and mobilities up to 12 cm²/V s. Inverters fabricated from these transistors exhibit maximum gain of 196 and uncertainty level of 0.36 V, outperforming inverters based on TMISFETs. [ABSTRACT FROM AUTHOR]