PhD Thesis_RuiMSMartins.pdf - RUN UNL

In-situ XRD studies during growth of Ni-Ti SMA films and their complementary ex-situ characterization
128 min
70 min
(a)
Fig. 3.19: Bright field X-TEM micrographs of the films deposited on thermally oxidized Si
substrates at ≈ 470°C; (a) without V b , (b) with a V b of −45 V.
(b)
It should be remembered that the chamber is equipped with two magnetrons
positioned at a distance of 100 mm from the substrate and tilted 30° away from the substrate
normal (see Fig. 2.6). To avoid cross contamination of the two targets cylindrical chimneys
are mounted on the magnetrons. During the deposition, the magnetron with the Ni-Ti alloy
target was running at a power of 40W and the one with the pure Ti target was running at a
power of 20W. The results presented in Fig. 3.19 suggest that the geometry of the deposition
process has an important role on the development of tilted columns. They are inclined towards
the Ni-Ti magnetron (higher power applied – higher incident flux).
Additional X-TEM observations were
performed along the film thickness to
study this effect (Ni-Ti film deposited at
≈ 470°C on thermally oxidized Si(100)
without V b ). By choosing a spot from a
SAED pattern, associated with (100) of
the B2 phase, the respective grains showed
up as bright regions in the corresponding
X-TEM dark field image of Fig. 3.20.
Fig. 3.20: X-TEM dark field image [Ni-Ti film
deposited at ≈ 470°C on thermally oxidized Si(100)
without V b ] resulting from the selection of a spot
associated with B2(100). The respective grains show
up as bright regions in the X-TEM micrograph.
Chapter 3 – Results 117