We firstly performed the reactive air wetting and brazing of Al₂O₃ ceramic using the Ag-(0.5‒12)Nb₂O₅ fillers, where the Nb₂O₅ can react with liquid Ag and O₂ from air to generate AgNbO₃. The contact angle of Ag-Nb₂O₅/Al₂O₃ system almost linearly decreases from ~71.6° to 32.5° with the Nb₂O₅ content increasing, and the joint shear strength reaches the maximum of ~65.1 MPa while employing the Ag-4Nb₂O₅ filler, which are mainly related to the formation and distribution of AgNbO₃ phase at the interface. Moreover, the interfacial bonding and electronic properties of related interfaces were investigated by first-principles calculations. The calculated works of adhesion (W_a) of Ag(111)/Ag-O-AgNbO₃(001) and AgNbO₃(001)/Al₂O₃(100) interfaces are higher than that of Ag(111)/Al₂O₃(110) interface, indicating the good reliability of Ag/AgNbO₃/Al₂O₃ structure. The relatively large interfacial charge transfer indicates the formation of Ag-Ag, Al-O and Ag-O bonds in the Ag/AgNbO₃/Al₂O₃ structure, which can contribute to the interfacial bonding.

The wettability of the metal/SiC system is not always excellent, resulting in the limitation of the widespread use of SiC ceramic. In this paper, three implantation doses of Si ions (5 × 10¹⁵, 1 × 10¹⁶, 5 × 10¹⁶ ions/cm²) were implanted into the 6H-SiC substrate. The wetting of Cu-(2.5, 5, 7.5, 10) Sn alloys on the pristine and Si-SiC were studied by the sessile drop technique, and the interfacial chemical reaction of Cu-Sn/SiC wetting couples was investigated and discussed. The Si ion can markedly enhance the wetting of Cu-Sn on 6H-SiC substrate, and those of the corresponding contact angles (θ) are raised partly, with the Si ion dose increasing due to the weakening interfacial chemical reactions among four Cu-Sn alloys and 6H-SiC ceramics. Moreover, the θ of Cu-Sn on (Si-)SiC substrate is first decreased and then increased from ~62° to ~39°, and ~70° and ~140°, with the Sn concentration increasing from 2.5%, 5% and 7.5% to 10%, which is linked to the reactivity of Cu-Sn alloys and SiC ceramic and the variation of liquid-vapor surface energy. Particularly, only a continuous graphite layer is formed at the interface of the Cu-10Sn/Si-SiC system, resulting in a higher contact angle (>40°).

This paper presents a novel thermopile chip in which the resonant cavity structure was fully utilized as an absorber by an optical design. The resonant cavity absorber structure was designed using Al as anthe bottom reflective metal layer, air as the intermediate dielectric layer, and SiO₂/TiN/Si₃N₄ sandwich layers as the top absorption layer, while the bottom reflective metal (Al) was deposited on the cold junctions of the thermopile. The simulation and calculation results show that the thermopile chip with resonant cavity absorber structure not only has great infrared absorption in the wide infrared absorption range but also can effectively prevent the cold junctions from absorbing infrared radiation and inhibit the rise of temperature. As a result, the temperature difference between the hot junctions and the cold junctions is increased, and the responsivity of the thermopile chip is further improved. Moreover, the duty cycle of the thermopile chip is greatly improved due to the double-layer suspension structure. Compared with the traditional thermopile chip structure, the sizes of the thermopile chip with the resonant cavity absorber structure can be further reduced while maintaining responsivity and specific detectivity.