Papers by Keyword: Al Thin Film

Abstract: We developed a novel KrF excimer laser doping system for 4H-SiC power devices, and demonstrated laser doping of 4H-SiC with Al thin film deposited on the surface. As seen from the results of the Al depth profile, high concentration implantation (~ 10²¹ cm^-3 at the surface) of Al was achieved by laser ablation of the Al thin film. A high, built-in-potential (~3.5 V) of the pn junction diode was clearly seen in the I-V curve. In addition, the contact resistivity of the deposited Al/Ti electrodes on the surface was 1.9 × 10⁻⁴ Ωcm² by TLM (Transmission Line Model). It was confirmed that a high concentration of Al doping and low contact resistivity were achieved by the KrF excimer laser doping system.

Abstract: Diffusion bonded joints of Ti alloys and Al alloys are widely applied in chemical, nuclear, aerospace industries. In the present study, TC4/Al thin film/1060 Al joints were bonded successfully by means of diffusion bonding under low temperature. The microstructure and mechanical properties of the joints were investigated by SEM,XRD and shear strength test. The results showed that the highest shear strength of TC4/Al thin film/1060 Al joints was 80.2 MPa. With the increasing of temperature, the shear strength increases firstly and then almost remains the same. Ti and Al elements diffused to each other in the bonding process and the intermetallic compounds can’t be found. The fracture of the joint had taken place in the 1060 Al/Al thin film rather than in the TC4/Al thin film and the fracture way of the joints was ductile fracture.

Abstract: Al thin films were prepared over different substrates at various process conditions using DC sputtering. The surface topography of all prepared films was examined using AFM technique. Very smooth, uniform and dense surface were observed for Al films coated over Glass substrates. The observed particle size was nano scale (20 -70 nm) for Glass substrates. Sputtering power showed immense effect on surface roughness with respective to Ar gas flow rate. Noticeable change on surface with large particles was observed in Copper substrates at various sputtering power and gas flow rate.

Abstract: Thin metal films often play an important role as structural elements or reflective surfaces in MEMS applications. Mechanical properties of the films are important due to their influence on the performance of MEMS devices that involve bending or stretching metal parts. In order to gain a better understanding of the mechanical behavior of thin metal films, we have developed a novel bulge system and measured mechanical properties of aluminum thin films. The thin films were prepared by e-beam evaporation of high purity Al onto 2 or 3mm ×12 mm rectangular silicon nitride membrane windows in silicon frames. N2 gas was used to pressurize and thus bulge the membranes. The bulge height was measured based on changes of capacitance between the membrane and a fixed, closely spaced electrode. This apparatus provides resolution of approximately 50 nm in bulge height at a data acquisition rate of 100/sec and provides strain rates in the membrane up to 10-5/sec. The stability of the apparatus allows stress relaxation measurements to be made to times of many hours. Time dependent elastic modulus changes of 1
m Al films were measured over periods of times under constant stress.