ZnO-based metal-semiconductor field-effect transistors on glass substrates

摘要

We investigate the influence of quartz glass and borosilicate glass substrates on the electrical properties of ZnO-based metal-semiconductor field-effect transistors (MESFETs). The n-type ZnO thin-film channels were grown by pulsed-laser deposition and MESFETs were processed by reactive dc sputtering of Ag_xO-Schottky gate contacts. All devices are in the normally-off state. They exhibit very low off-currents in the range of 10~(-13) A and on/off ratios of maximum 6 decades. The channel mobilities are highest for ZnO on quartz with 1.3cm~2/Vs. The glass substrates introduce a compensating effect on the conduction of the ZnO channel resulting in higher on/off-voltages and lower on-current.