High-mobility ZnVxOy/ZnO conduction path in ZnO/V/ZnO multilayer structure.

In this study, a 300 °C-annealed 3 × 4 V/ZnO multilayer structure demonstrates the lowest resistivity (3.82 × 10⁻³ Ω cm) and the highest mobility (18 cm²/V s) among the studied V/ZnO multilayer structures. By measuring the energy bandgap (E_g), work function (Φ), and electron affinity (χ) by ultraviolet photoelectron spectroscopy and photoluminescence analysis, the corresponding energy band diagram at the ZnV_xO_y/ZnO interface can be constructed. A potential is observed at the ZnV_xO_y/ZnO interface, which induces the two-dimensional electron gas (2DEG) effect, and this is attributed to the high-mobility conduction path. The potential well directly relates to the Φ difference between the ZnO and ZnV_xO_y layers, which is determined to be 0.22, 0.46, and −0.1 eV for the as-deposited, 300 °C-annealed, and 500 °C-annealed V/ZnO multilayer structures, respectively. The 300 °C-annealed V/ZnO multilayer structure could possibly have the largest depth in the potential well. This supports the 2DEG mechanism for the high mobility of the 300 °C-annealed V/ZnO multilayer structure. [ABSTRACT FROM AUTHOR]