**4. Structural characterization of the films through X-ray diffraction (XRD) and transmission electron microscopy (TEM)**

With the addition of Si, it has been found that the microstructure of MeN films changes, and this change will depend on Si. Three types of microstructure have been observed in function of Si content: polycrystalline films with low Si content up to 3 at.%, nanocrystalline films with 3–10 at.% (nanocomposite: nanocrystalline and amorphous phase), and with a Si content above 10 at.%, the films are amorphous. These values on the silicon content are obtained for Ti▬Si▬N deposited films with different Si contents [97], but may change depending on MeN. In our case, the microstructure ZrN▬Si deposited films were characterized by XRD and TEM techniques. **Figure 3** shows the XRD pattern of ZrN films with different Si contents deposited on the common glass substrate. **Figure 3** exhibits diffraction peaks corresponding to fcc-ZrN (pdf. 01-078-1420) for the ZrN film without silicon (black color). The addition of Si, red and blue color, indicates that the diffraction peak of the ZrN (111) tends to broaden, while the ZrN (200) peak disappears as Si content increased. The broadening of the peak may be due to the formation of nanocrystals of cubic ZrN and tetragonal ZrO2, reported in the 2θ position 33.83° (pdf. 01-078-1420) and 30.27° (pdf. 00-050-1089), respectively. The crystalline size for ZrN films is <10 nm, which was determined for the Scherrer equation, and with the addition of Si, the crystalline size decreased until 5 nm. The XRD evidenced that Si addition generated a refinement of grain, which is related with a broadening of the diffraction peaks. With a high Si content (15 at.%), the film is amorphous.

To study the structure of the ZrN▬Si film with Si content of 8 at.% in more detail, transmission electron microscopy with selected area electron diffraction (SAED) was done. **Figure 4** shows the SAED pattern of ZrN + 1Si film. It shows the presence of the (111), (200), and (220) diffraction rings, which indicate a fcc-ZrN structure, but the (111) diffraction ring is very broad, which is in very good agreement with the XRD results in the same d-spacing from 0.295 to 0.262 nm.

In addition, this ring broadens may be related with a mixture of phases, such as: ZrN, ZrO2 and Si3N4 as we can see in **Figure 5**. This figure shows the XRD pattern of ZrN + 1Si film and the crystallographic databases for ZrN (pdf. 01-078-1420), ZrO2 (pdf. 00-050-1089) and Si3N4 (pdf. 00-033-1160).

**Figure 3.** *The XRD patterns of the ZrN*▬*Si films with different silicon contents.*

#### **Figure 4.**

*(a) SAED pattern of ZrN + 1Si film. The diffraction ring, from 0.295 to 0.262 nm, is diffused possibly by the presence of various crystalline phases.*

#### **Figure 5.**

*The XRD pattern of the ZrN + 1Si film with crystallographic databases for ZrN (cubic), ZrO2 (tetragonal), and Si3N4 (hexagonal).*

The different crystallographic phases present in the ZrN + 1Si film were analyzed by phase contrast images, **Figure 6**. The existence of nanocrystals and the Fast Fourier Transform (FTT) in **Figure 6b** confirms the presence of the diffraction rings observed in **Figure 4**.

However, this figure allows separating two rings at the lowest d-spacing, which may confirm the hypothesis of a mixture of phases, as observed with XPS and XRD results. According to ZrN (01-078-1420) and ZrO2 (00-050-1089) pattern diffraction files, the interplanar distances in **Figure 6b** correspond to the ZrN face center cubic and ZrO2 tetragonal. Finally, the XPS, XRD, and HRTEM results show that with a Si content 0 at.%, the ZrN film is polycrystalline, with a 8 at.%, the film is nanocrystalline (ZrN and ZrO2 nanocrystalline), and possibly, with a Si3N4 amorphous matrix and with a 15 at.%, the Zr▬Si▬N film is amorphous.

Various published literatures have reported that electrical, optical, mechanical, and electrochemical properties of the nanocomposite films depend on their nanostructure. These works have found that with the addition of silicon to binary MeN,

**31**

**Table 5.**

*Effect of Silicon Content in Functional Properties of Thin Films*

and potentiodynamic polarization were carried out.

*the presence of two different crystalline phases between 0.295 and 0.262 nm.*

of nitration of the SiNx grain boundary phase [98].

*Values of resistivity the ZrN with different Si contents.*

**5. Electrical properties**

**Figure 6.**

hardness, thermal stability, and corrosion resistance of the films can be improved. In order to illustrate the relationship between the microstructure and functional properties, measurements of resistivity, reflectance, transmittance, nanohardness,

*(a) HR-TEM image of ZrN + 1Si film and (b) SAED pattern of the image (a). The results allow to identify* 

Electrical resistivity and sheet resistance measurements were obtained through the van der Pauw method for the Zr▬Si▬N deposited films, and their values were calculated and listed in **Table 5**. The results evidence that the electrical resistivity increases from 4.40 × 10<sup>−</sup><sup>4</sup> Ω cm (free Si) to 77.99 Ω cm (with 8 at.% Si) with the addition of silicon. This increase on the resistivity has been reported by other authors in different nanocomposites [54, 98]. They have found that depending on the chemical composition and electrical nature of the amorphous phase and nanocrystalline phase, the resistivity of Me▬Si▬N nanocomposite films can change. The electrical resistivity increases with increasing Si content, and the nanocomposite films have showed to have a structure of MeN nanocrystalline (conductor) surrounded of a SiNx amorphous phase (insulator). However, when the electrical resistivity behavior is independent to Si content, the resistivity is due to a direct percolation of the MeN1−x nanocrystalllines (conductors) separated by low degree

Therefore, the results obtained evidenced the formation of Zr▬Si▬N nanocomposite films with ZrN nanocrystallites embedded in the amorphous phase of SiNx, and the increase in the electrical resistivity with the Si addition is due to an increase in the thickness of SiNx layer that covers the nanocrystallites. The grain boundary scattering model is used for explaining the electrical conductivity in nanocomposite films [98].

**Film Silicon (at.%) Resistivity (**Ω **cm) Sheet resistance (**Ω**/**∎**)**

ZrN 0 4.40 × 10<sup>−</sup><sup>4</sup> 5.35 ZrN + 1Si 8 77.99 817006.68 *The sample with a 15 at.% Si was not possible to measure the electrical resistivity due to high resistivity.*

*DOI: http://dx.doi.org/10.5772/intechopen.85435*

*Effect of Silicon Content in Functional Properties of Thin Films DOI: http://dx.doi.org/10.5772/intechopen.85435*

**Figure 6.**

*Silicon Materials*

**30**

**Figure 5.**

**Figure 4.**

*presence of various crystalline phases.*

*and Si3N4 (hexagonal).*

rings observed in **Figure 4**.

*The XRD pattern of the ZrN + 1Si film with crystallographic databases for ZrN (cubic), ZrO2 (tetragonal),* 

*(a) SAED pattern of ZrN + 1Si film. The diffraction ring, from 0.295 to 0.262 nm, is diffused possibly by the* 

The different crystallographic phases present in the ZrN + 1Si film were analyzed by phase contrast images, **Figure 6**. The existence of nanocrystals and the Fast Fourier Transform (FTT) in **Figure 6b** confirms the presence of the diffraction

However, this figure allows separating two rings at the lowest d-spacing, which may confirm the hypothesis of a mixture of phases, as observed with XPS and XRD results. According to ZrN (01-078-1420) and ZrO2 (00-050-1089) pattern diffraction files, the interplanar distances in **Figure 6b** correspond to the ZrN face center cubic and ZrO2 tetragonal. Finally, the XPS, XRD, and HRTEM results show that with a Si content 0 at.%, the ZrN film is polycrystalline, with a 8 at.%, the film is nanocrystalline (ZrN and ZrO2 nanocrystalline), and possibly, with a Si3N4 amor-

Various published literatures have reported that electrical, optical, mechanical, and electrochemical properties of the nanocomposite films depend on their nanostructure. These works have found that with the addition of silicon to binary MeN,

phous matrix and with a 15 at.%, the Zr▬Si▬N film is amorphous.

*(a) HR-TEM image of ZrN + 1Si film and (b) SAED pattern of the image (a). The results allow to identify the presence of two different crystalline phases between 0.295 and 0.262 nm.*

hardness, thermal stability, and corrosion resistance of the films can be improved. In order to illustrate the relationship between the microstructure and functional properties, measurements of resistivity, reflectance, transmittance, nanohardness, and potentiodynamic polarization were carried out.
