Improved Performance of InGaZnO Thin-Film Transistor With HfLaO Gate Dielectric Annealed in Oxygen

We have fabricated an amorphous InGaZnO thin-film transistor with HfLaO gate dielectric, and the influence of annealing the gate dielectric in oxygen on the device characteristics is investigated in detail. It is demonstrated that this annealing treatment can effectively suppress the negative oxide charges. In addition, the effect of this annealing treatment to suppress the acceptor-like border and interface traps has been discovered, which can explain the unusual phenomenon of counterclockwise hysteresis. Accordingly, a record-high saturation carrier mobility of 35.2 cm²/V ·s has been achieved for the device, and its threshold voltage, subthreshold swing, and on-off current ratio are 2.8 V, 0.292 V/dec, and 5.2 ×10⁶, respectively.