Ran-Jin Lin

Performance characterization of nonevaporable porous Ti getter films

The highly porous Ti film getters on (100) silicon substrates have been successfully grown by dc magnetron sputtering with varying glancing angle. The porous films were formed when the glancing angle was higher than 30°. The larger the glancing angle, the higher the porosity and specific surface area of the Ti films. The porous films were composed of isolated columnar crystals, and they have a larger capability to absorb oxygen than dense Ti films do. Differential scanning calorimetry analysis shows that the exothermal reaction temperature for a dense Ti film is 348°C. However, that for the porous Ti film ranges from 291to394°C. The suitable operation condition of porous Ti film getters can be evaluated using thermal desorption spectroscopy. The reversible and irreversible reactions may occur during gas desorption/adsorption of porous Ti films.

Microstructures, surface areas, and oxygen absorption of Ti and Ti–Zr–V films grown using glancing-angle sputtering

Highly porous Ti and TiZrV getter film coatings have been successfully grown on (100) silicon substrates using the glancing-angle direct-current magnetron sputtering method. The evolution of the microstructures of the Ti and the TiZrV films strongly depends on the sputtering flux rate, surface diffusion rate, nucleation rate, compositions, and self-shadowing geometry of the nuclei on the sputtering flux. The larger the glancing angle, the higher the porosity and specific surface area of the Ti and TiZrV films. The weight-gain results strongly depend on several factors, such as specific surface area, the surface structure of the getter film, the diffusion rate of O in the getter film, the reactivity of Ti, Zr, and V on O, and the order of the stabilities of Ti, Zr, and V oxides on the film’s surface. Porous Ti film absorbs oxygen better than porous TiZrV film does due to its higher surface area and the high diffusion rate of O in Ti films.

Catalytic Performance of Nanostructured Plate-type Cu and Cu-Fe on ZnO Nanorods for Steam Reforming of Methanol

The Cu-type and (Cu-Fe)-type film catalysts have been successfully prepared by the electroless plating on ZnO nanorods/stainless steel substrates. The microstructure features of the (Cu-Fe)-type films are high porosity and plate-type grains. The addition of iron into Cu-type film can improve the reducibility and the stability of the film catalysts. The reduction temperature of the (Cu-Fe)-type film catalysts decreases with increasing the addition of Fe. For Cu-5 at% Fe film, the reduction temperature is in the range of 195°C to 216°C as comparison in the range of 208°C to 233°C of the Cu-type film catalysts.

Preparation of Superconducting Tl-Ba-Ca-Cu-O Films by Diffusion Method

Superconducting Tl-Ba-Ca-Cu-O thin films on (100)MgO substrates have been prepared through interaction between vapor of thallium oxide and amorphous Ba-Ca-Cu-O films. The Ba-Ca-Cu-O films(1–2 µm) were prepared by rf magnetron sputtering process. The compositions of the targets were in the stoichiometric ratio of Ba:Ca:Cu = 1:1.8:1.5 and 1:3:2. The Ba-Ca-Cu-O film and Tl2O3 powders were wrapped in gold foil and were put into a heated tube furnace at 875–890°C for 1–10 min. The phases, superconducting properties and morphologies of the films strongly related to the treatment conditions. The best superconducting properties of the films are Tc(onset) = 125 K and Tc(zero) = 100 K. The reproductivity of this process was poor.

As‐Deposited Superconducting Y‐Ba‐Cu‐0 Films on GaAs Substrate by High Pressure Dc Sputtering Process

Superconducting Y‐Ba‐Cu‐0 thin films on (100)GaAs substrate have been successfully prepared by the high pressure DC sputtering process without further post‐annealing treatment. The target was compound Y 1 Ba 2 Cu 3 Ox made by solid‐state reaction. The sputtering gas was Ar‐50%0 2 , and total pressure was 1.5 torr. The substrate temperature was lower than 450°C. The best superconductivity of the film is Tc(onset) = 95K and Tc(R=0) = 40K. There are no mi‐crocracks on the film surface. The interdiffusion between the film and GaAs is limited.