**4.4 Pulsed laser deposition**

Pulsed laser deposition (PLD) is a novel growth technique for the growth of III-V semiconductors. PLD is an ultrahigh vacuum technique with the base pressure ranging from ~10−7 to 10−9 torr. As the growth takes place in a high vacuum, there is a slim chance of impurity incorporation due to contamination. In this technique, the pure material is ablated with the help of a high-energy laser at the same time the process

**Figure 7.** *Schematic diagram of PLD technique [70].*

gas plasma is introduced into the chamber. The laser-ablated material reacts with plasma species and migrates on the substrate surface [55]. Recently, this technique has been used to grow h-BN nanosheets and nanostructures. **Figure 7** shows the schematic diagram of the PLD technique for reference [78]. Glavin et al. reported this method's direct growth of BN nanosheets on the sapphire substrate. The growth was carried out using BN sintered target, which took place at 700°C growth temperature. The grown film exhibits a narrow Raman line width of ~30 cm−1, providing excellent crystalline quality. Later, the prepared films were probed for their UV response, and BN thin films show deep UV detection capabilities [79]. Velázquez et al. directly grown few monolayers of h-BN on Ag/SrTiO3(001). It was found that the grown h-BN monolayers were in the sub-millimeter range and scattered on the surface [80]. PLD is the immature technique for the growth of III-V semiconductors and is limited to small area fabrication. Very few reports on the growth of BN by the PLD technique are available. There is an immense need to study this technique to grow large-area films which could be of commercial use. There are several other methods to prepare 2D BN, like solvent exfoliation, solid state reactions, and substitution method, but only few potential large-scale preparation methods are described in this section.
