*3.3. Contact Angle*

Figure 3A–C depicts the contact angle (θ) of CoFeW films under three conditions, namely the as-deposited state, the temperature of 250 ◦C and 350 ◦C. The contact angles were measured with DI water and glycerol. The data in Table 1 show that the contact angles of the as-deposited CoFeW using DI Water were 81.2◦, 80.7◦, 81.5◦, 82.9◦, and 82.0◦. On the other hand, the contact angles with glycerol were 76.7◦, 78.1◦, 79.6◦, 75.5◦, and 75.9◦. Table 1 shows the contact angles of the Co40Fe40W20 films after annealing at 350 ◦C, measured with DI water and glycerol. As seen, the contact angles of the as-deposited CoFeW with DI water are 66.9◦, 69.8◦, 66.6◦, 69.1◦, and 66.8◦, and those with glycerol are 62.3◦, 65.0◦, 60.7◦, 67.6◦, and 65.3◦. Based on the above results, the contact angles of all Co40Fe40W20 thin films are less than 90◦, suggesting that Co40Fe40W20 thin films show changes in the direction of higher hydrophilicity. Table 1 shows that the contact angle decreased with the increase of post-annealing temperature. It shows the same behavior as C60 and ZnO [25–28].

(**C**)

**Figure 3.** Contact angles of the Co40Fe40W20 thin films under three conditions: (**A**) as-deposited, (**B**) after post-annealing at 250 ◦C, (**C**) after post-annealing at 350 ◦C with DI water: (a) 10 nm, (b) 20 nm, (c) 30 nm, (d) 40 nm, and (e) 50 nm. Contact angles of the Co40Fe40W20 thin films with glycerol: (f) 10 nm, (g) 20 nm, (h) 30 nm, (i) 40 nm, and (j) 50 nm.


**Table 1.** Comparing contact angle, surface energy, and grain size for Co40Fe40W20 thin films from different fabrication processes.
