AlScN films prepared by alloy targets and SAW device characteristics

In this paper,we reported a surface acoustic wave(SAW)device prepared and optimized by piezoelectric films containing AIN,AIScN(Sc-20 at%)and AIScN(Sc-30 at%)by reactive magnetron sputtering using Al and AISc alloy targets.We calculated the material intrinsic electromechanical coupling coefficient k_(t)^(2) of AlScN(Sc-20 at%)and AlScN(Sc-30 at%)which are much better than AIN.It can be explained by the lattice softening.Furtherly,the results were confirmed by transmission electron microscopy(TEM)observation of the microstructure.Then the SAW devices based on three thin films were tested by vector network analysis obtaining the device equivalent electro mechanical coupling coefficient k_(eff)^(2).The value of AIScN(Sc-20 at%)k_(eff)^(2),which equals to 1.94%,is higher than that of AIN and AIScN(Sc-30 at%)while the value of AIScN(Sc-30 at%)k_(t)^(2) is higher than that of others.It is shown in our study that the crystallinity and orientation of the material still have a greater impact on k_(eff)^(2) but it does not have influence on k_(t)^(2) in the actual device preparation process.

Approximate Design of Alloy Composition of Cathode Target

An empirical formula for composition demixing analysis in cathodic arc ion plating using alloy target is established based on the concepts of average charged state and relative demixing parameter. The level of composition demixing effect is presented by demixing degree of one element. For binary constituent alloy target, the composition change trend in coating is discussed and the limit of demixing degree for each element is determined. The content of one element with higher average charged state gets larger in coating than in alloy target, at meantime, the content of one element with lower average charged state gets less. For each one of the two constituents, the less the atom percent in alloy target, the larger the difference of its contents between the coating and the target. For triple constituent alloy target, the content change of one element with moderate average charged state is discussed in detail. Its content in coating getting larger or less is determined by the combination result of the contents of the other two elements in alloy target. For a given content of the element with moderate average charged state in triple alloy target, the content deviation level of that element from coating to alloy target will be not larger than that using binary alloy target containing only that element and one of the two others. According to the wanted coating composition, the composition design of alloy target is easily deduced from the formula.

Study of high-speed-impact-induced conoidal fracture of Ti alloy layer in composite armor plate composed of Ti-and Al-alloy layers

In order to understand the mechanism of conoidal fracture damage caused by a high-speed fragmentsimulating projectile in titanium alloy layer of a composite armor plate composed of titanium-and aluminum-alloy layers,the ballistic interaction process was successfully simulated based on the Tuler eButcher and GISSMO coupling failure model.The simulated conoidal fracture morphology was in good agreement with the three-dimensional industrial-computed-tomography image.Further,three main damage zones(zones I,II,and III)were identified besides the crater area,which are located respectively near the crater area,at the back of the target plate,and directly below the crater area.Under the high-speed-impact conditions,in zone II,cracks began to form at the end of the period of crack formation in zone I,but crack formation in zone III started before the end of crack formation in zone II.Further,the damage mechanism differed for different stress states.The microcracks in zone I were formed both by void connection and shear deformation.In the formation of zone I,the stress triaxiality ranged from2.0 to1.0,and the shear failure mechanism played a dominant role.The microcracks in zone II showed the combined features of shear deformation and void connection,and during the formation process,the stress triaxiality was between 0 and 0.5 with a mixed failure mode.Further,the microcracks in zone III showed obvious characteristics of void connection caused by local melting.During the zone III formation,the triaxiality was 1.0e1.9,and the ductile fracture mechanism was dominant,which also reflects the phenomenon of spallation.

Thin Film Chip Resistors with High Resistance and Low Temperature Coefficient of Resistance

High resistance thin film chip resistors(0603 type) were studied,and the specifications are as follows:1 k? with tolerance about ±0.1% after laser trimming and temperature coefficient of resistance(TCR) less than ±15×10-6/℃.Cr-Si-Ta-Al films were prepared with Ar flow rate and sputtering power fixed at 20 standard-state cubic centimeter per minute(sccm) and 100 W,respectively.The experiment shows that the electrical properties of Cr-SiTa-Al deposition films can meet the specification requirements of 0603 ty...