Structural and electrical properties of high-κ Bi2Mg2∕3Nb4∕3O7 pyrochlore films on silicon for possible gate dielectric applications

Abstract

Bi 2 Mg 2 ∕ 3 Nb 4 ∕ 3 O 7 pyrochlore films were deposited on p-type Si (100) substrates using radio frequency reactive magnetron sputtering technique. Rapid thermal annealing (RTA) in O2 ambient followed by RTA in N2 ambient was carried out. The structural, morphological, and chemical bonding features of these films were studied by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy. All the films exhibit smooth, homogeneous, continuous, crack free, and dense films surfaces with root-mean-square roughness values in the range of 1.91−4.16 Å. The films show high crystallization temperature at about 900 °C. High temperature annealing gives rise to more oxygen incorporation in the films with probable formation of silicate type bonding at the interface. Effective oxide charge density, flatband voltage, hysteresis, oxide trap charge density, and interface state density values are comparable to those of some of the most widely investigated high-k gate dielectrics. The values decrease with increasing annealing temperature. A minimum leakage current density of the order of ∼10−6 A∕cm2 at a bias voltage of −1 V has been obtained even after annealing at 800 °C. All the annealed films show high breakdown field values of more than 5 MV/cm.