*2.1.3. Drawbacks of PLD*

**Figure 8.** Textile material partially coated with ZnO nanostructures: (a) hydrophobic nanoparticle deposited in vac‐ uum, (b) hydrophilic thin film deposited in 13 Pa oxygen flux, and (c) hydrophobic thin film deposited in vacuum. Inset (a) and (c): water droplet in static mode and the measured CA images were acquired with a EOS 50D digital cam‐

12 Applications of Laser Ablation - Thin Film Deposition, Nanomaterial Synthesis and Surface Modification

**Figure 9.** Thickness profiles of TiN layers recorded by profilometry (Reproduced with permission from Ref. [24]).

**Figure 10.** SEM/EDX images recorded for ZrC/TiN multi‐layers deposited by PLD (Reproduced with permission from

A relevant case of multi‐structures ZrC/ZrN and ZrC/TiN is given for exemplification (**Figure 10**). The purpose of this research was to increase the hardness and the elastic modulus of protective coatings. Out of ZrC, ZrN, and TiN single layers, the best results were obtained in case of ZrC with a hardness of 27.6 GPa and a reduced modulus of 228 GPa [25]. For multi‐ structures, the hardness and reduced modulus increased to similar values between 32.4 and

33.2 GPa and between 251 and 270 GPa, respectively [26].

era (Canon).

Ref. [26]).

Because the plasma plume is expanding mainly in the *z* direction (see **Figure 11**), the deposition area is usually of a few square centimetres only. Special translation/rotation robotized substrate holders should be used for uniform coating of large substrate areas [9].

**Figure 11.** Schematic for the vapor cloud expansion after target irradiation by a laser pulse with energy over the abla‐ tion threshold.

Even though PLD deposition of organic materials was reported, generally, this deposition method is not suitable for such compounds—under the action of intense laser pulses, long organic chains can be broken, the deposited material being different from the original target material.

The most important disadvantage however, comes from the micronic and sub‐micronic aggregates (known in the literature as particulates or droplets) that hinder applications in fields requiring high finesse (micro or nano‐electronics). However, additional procedures in conjunction with PLD can drastically diminish the droplets in PLD films [27–29].
