Investigation of Al droplet wetting behavior on highly-oriented SiC.

In the integrated circuit industry, metal liquids are frequently in contact with chemical vapor deposited (CVD) SiC, and it is important to understand the interactions between CVD-SiC and metal droplets. In this study, the wetting behavior of Al on a highly oriented SiC surface was investigated, and the contact angle could be controlled from 6° to 153° at a wetting temperature (Twet) of 1573-1773 K; the obtained contact angle range was larger than that of polycrystalline silicon carbide (Twet = 873-1473 K, 9-113°) and single crystal silicon carbide (Twet = 873-1473 K, 31-92°). The presence of many dislocations at the Al/SiC interface increased the interfacial energy, resulting in a greater contact angle for Al on the 〈111〉-oriented SiC coating surface than on the 〈110〉 one.

Optimizing Electromagnetic Interference Shielding of Ultrathin Nanoheterostructure Textiles through Interfacial Engineering.

Strong electromagnetic wave reflection loss concomitant with second emission pollution limits the wide applications of electromagnetic interference (EMI) shielding textiles. Decoration of textiles by using various dielectric materials has been found efficient for the development of highly efficient EMI shielding textiles, but it is still a challenge to obtain EMI shielding composites with thin thickness. A route of interfacial engineering may offer a twist to overcome these obstacles. Here, we fabricated a Ni nanoparticle/SiC nanowhisker/carbon cloth nanoheterostructure, where SiC nanowhiskers were deposited by a simple manufacturing method, namely, laser chemical vapor deposition (LCVD), directly grown on carbon cloth. Through directly constructing a Ni/SiC interface, we find that the formation of Schottky contact can influence the interfacial polarization associated with the generation of dipole electric fields, leading to an enhancement of dielectric loss. A striking feature of this interfacial engineering strategy is able to enhance the absorption of the incident electromagnetic wave while suppressing the reflection. As a result, our Ni/SiC/carbon cloth exhibits an excellent EMI shielding effectiveness of 68.6 dB with a thickness of only 0.39 mm, as well as high flexibility and long-term duration stability benefited from the outstanding mechanical properties of SiC nanowiskers, showing potential for EMI shielding applications.

High-throughput growth of HfO2 films using temperature-gradient laser chemical vapor deposition.

The use of hafnia (HfO2) has facilitated recent advances in high-density microchips. However, the low deposition rate, poor controllability, and lack of systematic research on the growth mechanism limit the fabrication efficiency and further development of HfO2 films. In this study, the high-throughput growth of HfO2 films was realized via laser chemical vapor deposition using a laser spot with a large gradient temperature distribution (100 K mm-1), in order to improve the experimental efficiency and controllability of the entire process. HfO2 films fabricated by a single growth process could be divided into four regions with different morphologies, and discerned for deposition temperatures increasing from 1300 K to 1600 K. The maximum deposition rate reached 362 µm h-1, which was 102 to 104 times higher than that obtained using existing deposition methods. The dielectric constants of high-throughput HfO2 films were in the range of 16-22, which satisfied the demand of replacing the traditional SiO2 layer for a new generation of microchips.