Growth of highly oriented γ- and α-Al2O3 thin films by pulsed laser deposition

• Highly oriented film of γ-Al2O3 (400) || SrTiO3 (100) was obtained.
• Highly oriented film of α-Al2O3 (024) || α-Al2O3 (1 1̄02) was obtained.
• Highly oriented film of α-Al2O3 (006) || α-Al2O3 (0001) was obtained.
• This is the first time the α-Al2O3 epitaxial films are grown at 973 K.
• Surface morphology of the films shows the layer by layer growth.

Highly oriented aluminum oxide (Al2O3) thin films were grown on SrTiO3 (100), α-Al2O3 (11̄02), α-Al2O3 (0001) and MgO (100) single crystal substrates at an optimized oxygen partial pressure of 3.5×10−3 mbar and 700 °C by pulsed laser deposition. The films were characterized by X-ray diffraction and atomic force microscopy. The X-ray diffraction studies indicated the highly oriented growth of γ-Al2O3 (400) ǁ SrTiO3 (100), α-Al2O3 (024) ǁ α-Al2O3 (11̄02), α-Al2O3 (006) ǁ α-Al2O3 (0001) and α-Al2O3 (006) ǁ MgO (100). Formation of nanostructures with dense and smooth surface morphology was observed using atomic force microscopy. The root mean square surface roughness of the films were 0.2 nm, 0.5 nm, 0.7 nm and 0.3 nm on SrTiO3 (100), α-Al2O3 (11̄02), α-Al2O3 (0001) and MgO (100) substrates, respectively.