Abstract
In our work, metal-oxide-semiconductor capacitors and transistors with LaAlO3 (LAO), laminated HfO2/CeO2, and Sm2O3 gate dielectrics were fabricated. The current conduction mechanisms, the interfacial properties, and the electron mobility degradation mechanisms were studied. The dielectric films were deposited by radio frequency magnetron sputtering and examined by x-ray diffraction (XRD), secondary ion mass spectroscopy (SIMS), x-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The LaAlO3 films remained amorphous with post-deposition annealing up to 1000 °C for 5 s. The dielectric constant of LAO capacitors was 17.5. The leakage current density was relatively low at 7.6×10-5 A/cm2 for a voltage bias of -1 V due to the high electron barrier height of 1.8 eV at the Al/LaAlO3 interface. The Al/LaAlO3 barrier height and the effective electronic mass calculated from from Schottky emission and Fowler-Nordheim tunneling were 1.12 eV and 0.27 m0, respectively. The interfacial properties such as the surface-recombination velocity, the minority-carrier lifetime, and the effective capture cross section of surface states were extracted from the gated-diode measurement. The temperature dependence of electron mobility degradation mechanisms was studied from 11 K to 400 K. The rate of threshold voltage change with temperature (□VT/□T) was -1.38 mV/K. The electron mobility limited by surface roughness was proportional to Eeff-0.66 in the electric field of 0.93 MV/cm<Eeff<2.64 MV/cm at 300 K and the phonon scattering was proportional to T-5.6 between 300 K and 400 K.As for the interfacial properties of the laminated HfO2/CeO2/Si interface, the surface states density Dit was 9.78x1011 cm-2 ? eV-1. The surface-recombination velocity (s0) and the minority carrier lifetime in the field-induced depletion region (τ0,FIJ) measured from gated-diodes were about 6.11×103 cm/s and 1.8×10-8 s, respectively. The effective capture cross section of surface state (σs) was determined to be about 7.69×10-15 cm2.As for the conduction mechanisms in Sm2O3 thin films, the dominant conduction mechanism in the temperature range from 325 K to 500 K and at the electrical field from 0.08 to 0.81 MV/cm was Schottky emission. At 77 K and with the electrical field above 0.9 MV/cm, the conduction mechanism was Fowler-Nordheim tunneling. The Al/Sm2O3 electron barrier height and the effective electronic mass calculated from the conduction mechanisms were 0.82 eV and 0.13m0, respectively.