Photogating and electrical-gating of amorphous GaSnZnO-based inverter with light-transmitting gate electrode

Photoinverter and electrical-inverter applications of amorphous GaSnZnO thin-film transistors (GTZO-TFTs) with Al2O3 dielectrics were studied. The inverters were composed of two serially connected top-gate GTZO-TFTs with different gate electrodes: semitransparent conducting NiOx and opaque Al. Since the two electrodes have so different work functions as to properly arrange the respective threshold voltages of driver and load TFTs, our inverter exhibited a desirable voltage transfer characteristics with voltage gain of over 25 for electrical gating. A dynamic photogating was demonstrated with an output photogain of similar to 2 V as we applied a blue illumination onto semitransparent NiOx gate, through which the photons are transmitted to excite the trapped electrons at the Al2O3 dielectric/GTZO channel interface. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3598396]