Enhanced performance of indium zinc oxide thin film transistor by yttrium doping

The Y3+-doped indium zinc oxide thin film transistor devices were fabricated by the sol-gel spin-coating technique. The Y3+-doped indium zinc oxide thin film transistor operates in n-channel enhancement mode and exhibits a well-defined pinch-off and saturation region. Because yttrium ion possesses lower electronegativity (1.22) and standard electrode potential (−2.372 V), it can act as the carrier suppressor to reduce the carrier concentrations of indium zinc oxide (In:Zn = 1:1) thin films from 1.29 × 1020 to 3.05 × 1014 cm−3 with the increase of Y3+ doping concentrations from 0 to 12 mol%. In addition, Y3+ (12 mol%)-doped indium zinc oxide thin film has the minimal surface roughness (1.067 nm) and lowest trap states (5.14 × 1012 cm−2). Therefore, Y3+ (12 mol%)-doped indium zinc oxide thin film transistor possesses the optimum performance, and its field-effect mobility in the saturated regime, threshold voltage, on-off ratio, and S-factor are 4.76 cm2/Vs, 4.3 V, 1.32 × 106, and 2.9 V/decade, respectively.