p-Type oxides for use in transparent diodes

Several p-type oxides of the delafossite structure have been investigated in the hope that the conductivity and transparency will be high enough to render them useful in the manufacture of transparent p–n junction diodes and other transparent devices. The highest conductivity achieved to date has been 220 S/cm in CuCr 1− x Mg x O 2 thin films. Oxygen intercalation in CuSc 1− x Mg x O 2+ y films improves the conductivity at the expense of optical transparency. We have improved the conductivity of CuGaO 2-based films from 0.02 to 1 S/cm by substitution of Fe for Ga. p-Type conductivity has been demonstrated in an Ag-based delafossite film. A sputter-deposited AgCoO 2 film has a conductivity of 0.2 S/cm, a Seebeck coefficient of 230 μV/K and a band gap of 4.1 eV at room temperature. CuNi 2/3Sb 1/3O 2 films have been produced that are p-type conductors when doped with Sn.