Structural and mechanical properties of nanocrystalline Ga 2 O 3 films made by pulsed laser deposition onto transparent quartz substrates

This work reports on the correlation between structure, surface/interface morphology and mechanical properties of pulsed laser deposited (PLD) β -Ga 2 O 3 films on transparent quartz substrates. By varying the deposition temperature in the range of 25 °C–700 °C, ∼200 nm thick Ga 2 O 3 films with variable microstructure and amorphous-to-nanocrystalline nature were produced onto quartz substrates by PLD. The Ga 2 O 3 films deposited at room temperature were amorphous; nanocrystalline Ga 2 O 3 films were realized at 700 °C. The interface microstructure is characterized with a typical nano-columnar morphology while the surface exhibits the uniform granular morphology. Corroborating with structure and surface/interface morphology, and with increasing deposition temperature, tunable mechanical properties were seen in PLD Ga 2 O 3 films. At 700 °C, for nanocrystalline Ga 2 O 3 films, the dense grain packing reduces the elastic modulus E r while improving the hardness. The improved crystallinity at elevated temperatures coupled with nanocrystallinity, the β -phase stabilization is accounted for the observed enhancement in the mechanical properties of PLD Ga 2 O 3 films. The structure-morphology-mechanical property correlation in nanocrystalline PLD β -Ga 2 O 3 films deposited on quartz substrates is discussed in detail.