p-Type ${\hbox {Cu}}_{x}{\hbox {O}}$ Thin-Film Transistors Produced by Thermal Oxidation

Thin-films of copper oxide $({\hbox {Cu}}_{x}{\hbox {O}})$ were produced by thermal oxidation of metallic copper (Cu) at different temperatures (150–450 $^{\circ}{\hbox {C}}$ ). The films produced at temperatures of 200, 250 and 300 $^{\circ}{\hbox {C}}$ showed high Hall motilities of 2.2, 1.9 and 1.6 ${\hbox {cm}}^{2} {\hbox {V}}^{-1}{\hbox {s}}^{-1}$ , respectively. Single ${\hbox {Cu}}_{2}{\hbox {O}}$ phases were obtained at 200 $^{\circ}{\hbox {C}}$ and its conversion to CuO starts at 250 $^{\circ}{\hbox {C}}$ . For lower thicknesses $\sim$ 40 nm, the films oxidized at 250 $^{\circ}{\hbox {C}}$ showed a complete conversion to CuO phase. Successful thin-film transistors (TFTs) were produce by thermal oxidation of a 20 nm Cu film, obtaining p-type ${\hbox {Cu}}_{2}{\hbox {O}}$ (at 200 $^{\circ}{\hbox {C}}$ ) and CuO (at 250 $^{\circ}{\hbox {C}}$ ) with On/Off ratios of ${\hbox {6}}\times {\hbox {10}}^{1}$ and ${\hbox {1}}\times {\hbox {10}}^{2}$ , respectively.