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.