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We have investigated the contact resistivity of PtHf-alloy silicide (PtHfSi) to p-Si(100) with dopant segregation (DS) process. After the patterning of SiO 2 hard mask and heavily doped p+ diffusion region formation on n-Si(100) substrates, 20 nm-thick PtHf-alloy thin film with 10 nm-thick HfN encapsulating layer was in-situ deposited utilizing PtHf-alloy target by RF magnetron sputtering at room temperature. Then, BF 3 ion implantation was carried out for DS followed by the silicidation at 500°C/20 min in N 2 /4.9%H 2 ambient. After the Al electrode formation, sintering process was carried out at 400°C/20 min in N 2 /4.9%H 2 ambient. Ultra-low contact resistivity was achieved for fabricated PtHSi such as 7.6×10−8 Ωcm2 with the contact area (Ac) of 4.2 Ωm2 evaluated by cross-bridge Kelvin resistor (CBKR) method. The estimation method of contact resistivity was proposed, and 9.4Ω10−8 Ωcm2 was extracted for the scaled contact area.

An immersed tunnel is a kind of underwater transporting passage crossing a river, a canal, a gulf or a strait. It is built by dredging a trench on the river or sea bottom, transporting prefabricated tunnel elements, immersing the elements one by one to the trench, connecting the elements, backfilling the trench and installing equipments inside it (Gursoy et al., 1993). Compared with a bridge, an immersed tunnel has advantages of being little influenced by big smog and typhoon, stable operation and strong resistance against earthquakes. Due to the special economical and technological advantages of the immersed tunnel, more and more underwater immersed tunnels are built or are being built in the world. Building an undersea immersed tunnel is generally a super-large and challenging project that involves many key engineering techniques (Ingerslev, 2005; Zhao, 2007), such as transporting and immersing, underwater linking, waterproofing and protecting against earthquakes. Some researches with respect to transportation, in situ stability and seismic response of tunnel elements are seen to be carried out (Anastasopoulos et al., 2007; Aono et al., 2003; Ding et al., 2006; Hakkaart, 1996; Kasper et al., 2008). The immersion of tunnel elements was also studied (Zhan et al., 2001a, 2001b; Chen et al., 2009a, 2009b, 2009c). The immersion of a large-scale tunnel element is one of the most important procedures in the immersed tunnel construction, and its techniques involve barges immersing, pontoons immersing, platform immersing and lift immersing (Chen, 2002). In the sea environment, the motion responses of a tunnel element in the immersion have direct influences on its underwater positioning operation and immersing stability. So a study on the dynamic characteristics of the tunnel element during its interaction with waves in the immersion is desirable. Although, some researches on the immersion of tunnel elements were done in the past years, there is still much work remaining to study further. Also, the study on the immersion of tunnel elements under irregular wave actions is not seen as yet. The aim of the present study is to investigate experimentally the motion dynamics of the tunnel element in the immersion under irregular wave actions based on barges immersing