Abstract
Metal-oxide-semiconductor (MOS) capacitors and n-channel metal-oxide-semiconductor-field-effect-transistors (MOSFETs) with ZrO2 and Sm2O3 gate dielectrics were fabricated. The mobility degradation mechanisms of ZrO2 and Sm2O3-gated transistors were studied in the temperature range from 11K to 300K. N-MOSFETs with SiO2 gate dielectric was used as the reference. The effective electron mobility was measured by the split C-V method. The electron mobility of n-MOSFETs with ZrO2 and Sm2O3 gate dielectrics are 211 and 238 cm2/V-s, respectively. The variation of the threshold voltage and the electron mobility as a function of temperature was characterized. Comparing with SiO2-gated transistors, the electron mobility of ZrO2-gated n-MOSFETs is limited by additional Coulomb scattering at electric field above 0.33 MV/cm. The reason is most likely due to higher density of oxide trapped charges in the ZrO2 layer. Comparing with SiO2- gated transistors, the electron mobility of Sm2O3-gated n-MOSFETs is limited by additional phonon scattering at electric field above 0.22 MV/cm. The reason is most likely due to soft optical phonons in Sm2O3-gated n-MOSFETs.