Room temperature deposited oxide p-n junction using p-type zinc-cobalt-oxide

Oxide semiconductors are attractive materials for thin-film electronics and optoelectronics due to compatibility with synthesis on large-area, inexpensive glass and flexible plastic substrate. However, development of thin-film electronics has been hampered by the limited number of semiconducting oxides that are p-type. Here, we report on the properties of zinc-cobalt-oxide (Zn-Co-O) films, deposited at room temperature using pulsed laser deposition, that exhibit p-type conduction. Films are deposited at room temperature in a background of oxygen using a polycrystalline ZnCo(2)O(4) ablation target. The p-type conduction is confirmed by positive Seebeck coefficient and positive Hall coefficient. Both electrical resistivity and carrier density are dependent on oxygen background pressure used during deposition. Zn-Co-O films deposited in 50 mTorr oxygen pressure appear to be amorphous based on x-ray diffraction, and show an electrical conductivity as high as 21 S cm(-1). Distinct rectifying current-voltage characteristics are observed for junctions between Zn-Co-O and n-type InGaZnO films, exhibiting a threshold voltage of similar to 2.5 V. P-type Zn-Co-O appears promising for thin-film electronic device technology. (C) 2010 American Institute of Physics. [doi:10.1063/1.3415543]