Direct Current Sputtering Power Research Articles

Modulation of the microstructure, optical properties and electrical properties of zinc-doped nickel oxide films via direct current sputtering power

Zinc-doped NiO (NiO:Zn) films were direct-current-magnetron sputtered on the glass substrates. The modulation of the properties of the films via sputtering powers (Pspu) was especially studied. The conducting transition from p to n type was also proposed in mechanism. The NiO:Zn films are all preferentially 〈111〉 oriented. The films with high Pspu almost have small lattice distortion due to the improved crystallization caused by the thermal effect and the Zn element doping. The films begin to exhibit the n-type conduction at 90 W Pspu. The conducting transition from p to n type is mainly attributed to the occupation of Ni vacancies by Zn2+ and the interstitial Zn, and the improved n-type conduction in Pspu range of 140 W through 160 W to the increase in content of the interstitial Zn atoms. The absorption edge of the NiO:Zn films remaining at about 3.7 eV is slightly affected by the increase in Pspu, showing that the doping of the Zn element in the NiO is not mainly in the form of the Ni vacancies occupying ions.

A Co-Sputtering Process Optimization for the Preparation of FeGaB Alloy Magnetostrictive Thin Films.

A co-sputtering process for the deposition of Fe0.8Ga0.2B alloy magnetostrictive thin films is studied in this paper. The soft magnetic performance of Fe0.8Ga0.2B thin films is modulated by the direct-current (DC) sputtering power of an FeGa target and the radio-frequency (RF) sputtering power of a B target. Characterization results show that the prepared Fe0.8Ga0.2B films are amorphous with uniform thickness and low coercivity. With increasing FeGa DC sputtering power, coercivity raises, resulting from the enhancement of magnetism and grain growth. On the other hand, when the RF sputtering power of the B target increases, the coercivity decreases first and then increases because of the conversion of the films from a crystalline to an amorphous state. The lowest coercivity of 7.51 Oe is finally obtained with the sputtering power of 20 W for the FeGa target and 60 W for the B target. Potentially, this optimization provides a simple way for improving the magnetoelectric coefficient of magnetoelectric composite materials and the sensitivity of magnetoelectric sensors.

Microstructure and adsorption characteristics of Zr–Co–RE getter films deposited using krypton as sputtering gas

The vacuum level in micro-electro-mechanical system devices needs to be achieved and maintained using non-evaporable getter film technology. Zr–Co–RE getter films are deposited by direct current (DC) magnetron sputtering using krypton (Kr) as the sputtering gas. The influence of sputtering gas pressure and DC sputtering power on the microstructure and adsorption characteristics of films is investigated. Zr–Co–RE films deposited at different gas pressures all grow in a columnar shape. Films grown at low Kr pressures are relatively dense and have a structure with fewer cracks, whereas high Kr pressures result in a uniform cluster and columnar structure with more gaps and micro-cracks. In addition, it is revealed that DC sputtering power has great influence on the film structure and adsorption performance. The films deposited at low sputtering power contain more micro-cracks, which are distributed uniformly. At high sputtering power, the cluster structure is not obvious. Consequently, high Kr pressures and low sputtering power are beneficial to improve the adsorption performance. Hydrogen adsorption tests are carried out using a special vacuum system, keeping the pressure constant. The highest initial adsorption speed is 89 (ml/s)/cm2, obtained at 4.0 Pa Kr pressure and 300 W sputtering power. Meanwhile, the Zr–Co–RE films deposited under these conditions have excellent adsorption stability.

Structural and optical investigations on direct current (DC) magnetron sputtered CZTS thin film

Cu2ZnSnS4 has been grown by using DC sputtering onto the soda-lime glass (SLG). A single ceramic target has been used to deposit thin films. The deposition has been carried out at various substrate temperatures from room temperature to 400 ℃ at constant 50 W DC sputtering power. The structural and optical measurements were performed using the x-ray diffractometer and UV–Vis-NIR spectrophotometer. The study reveals the dependence of the preferred orientation of crystal on the substrate temperature. At room temperature, the CZTS thin films show amorphous crystalline nature. While crystallinity has been improved with an increase in temperature. CZTS thin films deposited at 400 ℃ show a highly crystalline structure with preferred orientation to the (112) plane. Optical investigation demonstrates a decrease in band gap upon the increase in substrate temperature. Urbach energy and crystallite size show good agreement.

High efficiency perovskite solar cells using DC sputtered compact TiO2 electron transport layer

High conductivity and transparency of the electron-transporting layer (ETL) is essential to achieve high efficiency perovskite solar cells (PvSCs). Generally, titanium dioxide (TiO2) has been extensively utilized as an ETL in PvSCs. Both surface roughness and uniformity of the compact-TiO2 (C-TiO2) can influence the efficiency of the PvSC. This work investigates the optimization of the direct current (DC) sputtering power and the ratio of argon (Ar) to oxygen (O2) plasma to achieve high quality ETL films. The effect of changing the DC sputtering power on the C-TiO2 films and subsequently on the overall efficiency was studied. The electrical and optical properties of the C-TiO2 layer were characterized for various DC powers and different ratios of Ar to O2 plasma. It was found that the optimum preparation conditions for the C-TiO2 films were obtained when the DC power was set at 200 W and a flow rate of 6 sccm Ar and 12 sccm O2. A power conversion efficiency (PCE) of 15.3% in forward sweep and 16.7% in reverse sweep were achieved under sunlight simulator of 100 mW/cm2. These results indicate that significant improvement in the efficiency can be achieved, by optimizing the C-TiO2 layer.

Influence of tantalum's crystal phase growth on the microstructural, electrical and mechanical properties of sputter-deposited tantalum thin film layer

High melting point refractory tantalum (Ta) metal is frequently grown into thin film layer for many applications in biomedical implants, microelectronic devices and micro-level mechanical systems. Tantalum growth mechanism is still in debate and the inconsistent crystal phase outcome has puzzled many, though it is certain that the properties of the grown film are highly dependent on the formed crystal phase configuration. The microstructure, surface morphology, crystal orientation and residual stress of the sputter-deposited Ta thin films using direct current (DC) magnetron sputtering technique are studied at 0.4 Pa – 2 Pa of sputtering pressure, 100 W – 250 W of DC sputtering power on bare silicon and silicon dioxide substrate and 10 min – 50 min of sputtering duration. α-phase Ta is preferably grown at high sputtering time (high thickness) and high DC sputtering power (high growth rate). The sputtering pressure affects the thin film's microstructural porosity while the sputtering power controls the crystallisation's quality. Both sputtering pressure and power affect the generated argon plasma in the DC magnetron sputterer where α-phase Ta is preferably formed at high plasma. The presence of 3 μm silicon dioxide underlayer makes no difference compared to bare silicon substrate. Our study reveals that β-phase Ta is grown first irrespective of sputtering conditions and then transformed into α-phase Ta after reaching a certain thickness. The grown major α-phase content promotes small thin film sheet resistivity (58.9 μΩcm – 86.1 μΩcm) and is suspected to be the dominant factor that increases the compressive stress within the thin film layer and reduces the adhesion of Ta layer onto the substrate surface. The study has given a new insight in controlling the conductivity and adhesion level of Ta thin film based on the grown phase layer.

Effects of DC sputtering power and rapid thermal processing temperature on tungsten disulfide (WS2) thin films

For the direct formation of two-dimensional (2D) tungsten disulfide (WS2) thin films with higher productivity and lower process temperature than conventional chemical vapor deposition (CVD), WS2 thin films were deposited on a sapphire glass substrate by direct current (DC) sputtering and subsequent rapid thermal processing (RTP). From the optical investigation by atomic force microscopy (AFM), it was possible to stable surface and observe more improvements at higher RTP temperatures irrespective of sputtering power. Hall measurements showed higher resistivity and lower carrier density at higher DC sputtering power in spite of the constant carrier mobility. Raman spectrum results showed lateral vibration of tungsten and sulfur atoms at temperatures above 700 °C. The directly formed WS2 thin films showed the improvements in structural and electrical characteristics as a semiconductor layer.

Electrical resistivity and transmittance properties of Al and Ga-codoped ZnO thin films

Films were deposited on glass substrates by sputtering gallium-doped zinc oxide (GZO) (Ga2O3: 90 wt%, ZnO: 10 wt%) and aluminum-doped zinc oxide (AZO) (Al2O3: 3 wt%, ZnO: 97 wt%) targets simultaneously using a direct-current (DC)/radio-frequency (RF) magnetron cosputtering system. The concentration of gallium (Ga) in the film was varied by using different RF powers for sputtering the GZO target with the DC power for sputtering the AZO target fixed. A minimum resistivitywas obtained at an RF sputtering power of 200 W for the GZO target when the DC sputtering power for the AZO target was fixed at 60 W. It was found that the resistivity of AZO thin films (6.40 × 10−3 Ω-cm for 0 W) could be lowered by more than one order by cosputtering AZO and GZO targets to make AGZO thin films (2.14 × 10−3Ω-cm for 200 W) without lowering their transmittance at all. In addition, the origin of the enhancement in the electrical property of the AZO by additional Ga doping is discussed.