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

Abstract

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 (−2.372V), 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 3.05×1014cm−3 with the increase of Y3+ doping concentrations from 0 to 12mol%. In addition, Y3+ (12mol%)-doped indium zinc oxide thin film has the minimal surface roughness (1.067nm) and lowest trap states (5.14×1012cm−2). Therefore, Y3+ (12mol%)-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 4.76cm2/Vs, 4.3V, 1.32×106, and 2.9V/decade, respectively.