**4. Synthesis method of TiO2**

TiO2 thin films were successfully synthesis by several techniques such as pulsed laser deposition (PLD), molecular beam epitaxy (MBE), RF magnetron sputtering, electrodeposition, sol–gel, hydrothermal, spin-spraying, spin coating, successive ionic layer adsorption and reaction (SILAR), chemical vapor deposition (CVD) and chemical bath deposition (CBD).

### **4.1 Pulsed laser deposition (PLD) method**

The technique of PLD is extremely simple which has been used to deposit high quality films. The technique uses high power laser pulses to melt, evaporate and ionize material from the surface of a target to the substrate (**Figure 6**). *A. Ishii* et al. [8] have elaborated TiO2 film into glass substrates. For the period of deposition, the pressure of PO2 in PLD chamber was around 1 to 9 Pa and the temperature was controlled by an infrared lamp heater and a Si plate from room temperature to 600°C for 20 min to make 100–150 nm thick. TiO2 thin films showed excellent optical properties, with n = 3.14 and k < 0.05 at λ = 400 nm.
