Engineering Materials and Processes phần 5 pptx

Thermal Stability 47

Figure 4.3. Electrical resistivity of Ag, Ag(Al)-I, and Ag(Al)-II thin films on SiO2

substrates annealed at various temperatures in vacuum for 1 hour [6]

The relatively higher resistivity value of Ag thin film made in this study when

compared to bulk silver resulted from more surface scattering due to its thickness

and the incorporation of a small amount of oxygen during the thin film process.

For the Ag(Al) thin films, the resistivity of samples annealed at 400°C for 1 hour in

vacuum is decreased from the value of as-deposited samples. It is thought that the

enhancement of crystallization and grain growth of thin film obtained by the X-ray

diffraction analysis shown in Figure 4.2 contribute to the decrease of resistivity.

The resistivity of both Ag(Al)-I and Ag(Al)-II thin films is constant after annealing

at 400°C. The difference of absolute value of resistivity between two different

Ag(Al) thin films has also remained constant. This means that the Ag(Al) on SiO2

is a thermally stable solid solution as confirmed by RBS, XRD, and optical

microscopy. For pure Ag thin films, the resistivity of the sample annealed at 400°C

for 1 hour in vacuum is decreased slightly due to the crystallization and grain

growth although agglomeration is started.

However, resistivity is increased abruptly from 500°C. The Ag thin film on

SiO2 annealed at 600°C for 1 hour in vacuum has infinite resistivity since the

scattering effect of conduction electrons is increased. The conduction path is

reduced and lost eventually. This fact is consistent with RBS, microstructure

analysis explained above. The interesting fact is that the resistivity of Ag(Al)-II

thin films annealed at 400°C is lower than that of pure Ag thin film annealed at the