Oxygen pressure dependence of physical and electrical properties of LaAlO3 gate dielectric

High k LaAlO3 (LAO) films were deposited directly on silicon substrates in various oxygen pressures by laser molecular-beam epitaxy technique. The influence of oxygen pressures during film fabrication on the physical and electrical properties of LAO films was studied. High resolution transmission electron microscopy measurements indicate that the thermo stability of LAO films in contact with silicon substrates is greatly affected by oxygen pressures, and thicker interfacial layer would be expected for LAO films deposited in high oxygen pressure. Capacitance-voltage (C-V) and leakage current measurements indicate that the effective oxide thickness, leakage current, flatband voltage and hysteresis loop characteristics are affected by the oxygen pressure during film fabrication. Larger EOT, lower leakage current and smaller hysteresis loop is expected to be obtained for LAO films deposited in higher oxygen pressure or lower vacuum. When oxygen pressure is below or equal to 0.1 Pa, the absolute value of VFB increases with the decrease of oxygen pressure. When oxygen pressure is above 0.1 Pa, the VFB value begins to decrease slowly.