Performance Modulation in All-Solution-Driven InCaOₓ/HfGdOₓ Thin-Film Transistors and Exploration in Low-Voltage-Operated Logic Circuits

In current work, InCaOx thin films with different Ca-doping concentrations were prepared via solution-processed method. A systematic investigation was conducted to reveal the variation in the physical properties of InCaOx thin films as a function of Ca-doping concentration by using various characteristic measurements. Results not only demonstrate that Ca-doping can change the optical properties, microstructure, and surface roughness of In
₂
O
₃
thin films but also indicate that Ca-doping can effectively decrease oxygen vacancies in In
₂
O
₃
thin films. By measuring the electrical properties of InCaOx/HfGdOx thin-film transistors (TFTs) at a low operating voltage of 5 V, it is noteworthy that Ca-doping can improve the deteriorated performance of In
₂
O
₃
/HfGdOx TFT caused by excessive oxygen vacancies. As Ca-doping concentration reaches 0.5%, InCaOx/HfGdOx TFT manifests superior performances, including a larger μFE of 15.1 cm
²
V
^-1
s
^-1
and a higher ION/IOFF of 2.3 × 10
⁷
. Furthermore, the stability of In
₂
O
³
/HfGdO
_x
TFTs under positive bias stress is improved after Ca-doping. Finally, an inverter with a high gain of 6.0 is assembled on the basis of InCaOx/HfGdOx TFT. More importantly, these excellent performances of InCaOx/HfGdOx TFTs are achieved at a low operating voltage, which marks a giant step toward the achievement of low cost and low power consumption electrical devices.