Thickness Dependence of the Initial Oxidation Behaviors of Gd Films Grown on Si by Laser Molecular Beam Epitaxy

Gd thin films with different thickness （about 10 nm and 0.5 nm） were deposited on Si（100） by laser molecular beam epitaxy （LMBE）. Thickness dependence of the initial oxidation behaviors of Gd films was studied based on the in situ X-ray photoelectron spectroscopy （XPS） and ultraviolet photoelectron spectroscopy （UPS） analysis under ultra-high vacuum （UHV） condition. When the thin film is around 10 urn, the XPS results show that Gd is extremely reactive with oxygen forming Gd oxides and the oxides of Gd are easily hygroscopic. The UPS results show that the Gd 4fhas a double-peak structure and the double-peak structure of Gd 4fevolves into a single-peak feature after exposing to air. When the thickness of the Gd film decreases to about 0.5 urn, the reactivity of Gd film with oxygen is decreased by the diffusion of Si component into Gd layers based on the XPS and UPS results. It is suggested that the silicon atoms segregate at the grain boundaries of Gd film to form a barrier, which block the further diffusion of oxygen and water vapor into the Gd layers.

Phase control of magnetron sputtering deposited Gd_2O_3 thin films as high-κ gate dielectrics

Gd2O3 thin films as high-κ gate dielectrics were deposited directly on Si（001） substrates by magnetron sputtering at a pressure of 1.3 Pa and different temperatures. X-ray diffraction results revealed that all the films grown from 450 to 570 ℃ were crystalline, and the Gd2O3 thin films consisted of a mixture of cubic and monoclinic phases. The growth temperature was a critical parameter for the phase constituents and their relative amount. Low temperature was favorable for the formation of cubic phase while higher temperature gave rise to more monoclinic phase. All the Gd2O3 thin films grown from different temperatures exhibited acceptable electrical properties, such as low leakage current density （JL） of 10-5 A/cm^2 at zero bias with capacitance equivalent SiO2 thickness in the range of 6-13 nm. Through the comparison between films grown at 450 and 570 ℃, the existence of monoclinic phase caused an increase in JL by nearly one order of magnitude and a reduction of effective dielectric constant from 17 to 9.

Semiconductor performance of rare earth gadolinium-doped aluminum–zinc oxide thin film

Rare earth element gadolinium-doped aluminum–zinc oxide（Gd–AZO） semiconductor thin film material was deposited on both silicon and glass substrate by radio frequency（RF） sputtering at room temperature.Electrical properties and microstructure of Gd–AZO thin film were mainly modulated by altering O2 partial pressure（OPP） during the RF sputtering process.Scanning electron microscope（SEM） and X-ray diffraction（XRD） test were carried out to uncover the microstructure variation trend with the sputtering OPP,and amorphous structure which is beneficial to large mass industry manufacture was also demonstrated by the XRD pattern.Transmittance in visible light spectrum implies the potential application for Gd–AZO to be used in transparent material field.Finally,bottom gate,top contact device structure thin film transistors（TFTs） with Gd–AZO thin film as the active channel layer were fabricated to verify the semiconductor availability of Gd–AZO thin film material.Besides,the Gd–AZO TFTs exhibit preferable transfer and output characteristics.