Direct correlation and strong reduction of native point defects and microwave dielectric loss in air-annealed (Ba, Sr)TiO3

作者：Zeng Z Q; Podpirka A; Kirchoefer S W; Asel T J; Brillson L J^*

来源：Applied Physics Letters, 2015, 106(18): 182903.

DOI：10.1063/1.4919891

We report on the native defect and microwave properties of 1 mu m thick Ba0.50Sr0.50TiO3 (BST) films grown on MgO (100) substrates by molecular beam epitaxy (MBE). Depth-resolved cathodo-luminescence spectroscopy (DRCLS) showed high densities of native point defects in as-deposited BST films, causing strong subgap emission between 2.0 eV and 3.0 eV due to mixed cation V-C and oxygen Vo vacancies. Post growth air anneals reduce these defects with 2.2, 2.65, and 3.0 eV V-o and 2.4 eV V-C intensities decreasing with increasing anneal temperature and by nearly two orders of magnitude after 950 degrees C annealing. These low-defect annealed BST films exhibited high quality microwave properties, including room temperature interdigitated capacitor tunability of 13% under an electric bias of 40V and tan delta of 0.002 at 10 GHz and 40V bias. The results provide a feasible route to grow high quality BST films by MBE through post-air annealing guided by DRCLS.

• 出版日期2015-5-4