Na-doped ZnO nanorods fabricated by chemical vapor deposition and their optoelectrical properties

• P-ZnO:Na nanorods have been grown on Si substrates by a catalyst-free CVD method.
• P-ZnO:Na nanorods with Na concentration in the range of 1.2–2.1 at.% exhibit p-conductivity.
• P-ZnO:Na nanorods/ZnO/n-Si heterostructure shows good rectifying behavior.

Na-doped ZnO (ZnO:Na) nanorods have been grown on Si substrates by a catalyst-free chemical vapor deposition method. Element analysis reveals that the doping concentration of Na is in the range of 0.5–3.7 at.%. Morphological and electrical properties of the ZnO nanorods were found to be highly dependent on the Na concentration. Hall measurement indicates the realization of p-ZnO:Na nanorods with hole concentrations in the order of 1015 cm−3. Temperature dependent photoluminescence measurement down to 10 K confirms the shallow acceptor level, which is ∼132 meV. Desirable rectifying behavior has also been observed from the I-V characteristic of the p-ZnO:Na nanorods/ZnO/n-Si structure and the turn on voltage is ∼2.5 V.