Fabrication of p-type copper oxide thin-film transisters at different oxygen partial pressure

P-type copper-based oxide thin films are fabricated by DC reactive sputtering of copper at room temperature (RT) and studied as a function of oxygen partial pressure (O
PP
). Cu
2
O crystalline phase is observed at 10% O
PP
and it changes to CuO when O
PP
increases to 15%. The crystallinity of the deposited films decreases sharply when O
PP
increases to ≥20%. The p-type conductivity of the deposited films is identified by Hall measurements. Both the as-deposited and post-annealed bottom gate TFTs using CuO as active layers show significant field effect. The post-annealed CuO TFT with 30% O
PP
has the p-type characteristics with μ
FE
≈ 5 × 10
⁻³
cm
⁻²
/V·s, and an on/off ratio around 10
²
.