Complementary Inverter Circuits Based on p-Cu2O and n-ZTO Thin Film Transistors

This paper describes the fabrication of copper oxide and zinc tin oxide complementary inverters where both the p-type and n-type channels were deposited by RF magnetron sputtering. We have designed low-voltage and high gain complementary inverters by combining a set of p channel copper oxide and n channel zinc tin oxide thin film transistors (TFTs) with different aspect ratios, thus reducing the difference in mobility and threshold voltage between both types of TFTs. The complementary inverters with four different geometric aspect ratios were fabricated using top-contact configuration. The voltage gain increase with aspect ratio and a maximum value of 4.2 was reached for an aspect ratio of 2 (Wp:Wn = 7200 μm/3600 μm). The voltage gain was found to be dependent on the SS value of p-type TFTs. It is also noticed that an inverter having a geometric aspect ratio of 2 gave better voltage gain and noise margin values. For a VDD = 20 V the NMH and NML values are 7 V and 6.5 V, respectively.