Local chemical states and thermal stabilities of nitrogen dopants in ZnO film studied by temperature-dependent x-ray photoelectron spectroscopy

摘要

Local chemical states and thermal stabilities of N dopants in ZnO:N film are investigated by temperature-dependent x-ray photoelectron spectroscopy. Different types of N local states are detected, including N_2 molecules occupying O sites [(N_2)_O], -NO species, substitutional N atoms in O- and N-rich local environments (α- and β-N_O). Compared to the β-N_O, the α-N_O shows a better thermal stability up to 723 K. However, the transformation from α-N_O acceptor to undesirable (N_2)_O donor occurs above 743 K. The variation of N local states also affects Zn and O binding energies. Photoluminescence studies indicate the shallow acceptor nature of α-N_O.