Room-temperature growth of ultrasmooth AlN epitaxial thin films on sapphire with NiO buffer layer

Abstract

Room-temperature epitaxy of AlN thin films on sapphire (0001) substrates was achieved by pulsed laser deposition using an epitaxial NiO ultrathin buffer layer (approximately 6 nm thick). Four-circle x-ray diffraction analysis indicates a double heteroepitaxial structure of AlN (0001)/NiO(111)/sapphire (0001) with the epitaxial relationship of AlN [10-10] ‖ NiO [11-2] ‖ sapphire [11-20]. The surface morphology of room-temperature grown AlN thin films was found to be atomically smooth and nanostepped, reflecting the surface of the ultrasmooth sapphire substrate with 0.2-nm-high steps.

Room-temperature selective epitaxial growth of CoO (1 1 1) and Co3O4 (1 1 1) thin films with atomic steps by pulsed laser deposition

“…As a strategy for epitaxial growth, pulsed laser deposition (PLD) involves the ablation of high-energy film precursors from the target onto a substrate at a supersonic speed (∼10 4 m/s); this method is especially useful for nucleation at low temperatures, room temperature in particular. To date, we have reported the room-temperature heteroepitaxial growth of semiconductor thin films such as ZnO, CeO 2 , Sn-doped SnO 2 (ITO), and AlN as well as NiO as an epitaxial buffer layer [6][7][8][9].…”

Fabrication of semiconducting SrB6− thin films on ultrasmooth sapphire substrates by laser molecular beam epitaxy

“…We have previously investigated low-temperature epitaxial growth of functional ceramic thin films of oxides [13][14][15], nitrides [16,17], and diamond [18] by PLD or laser molecular beam epitaxy (MBE) using ultrasmooth sapphire (a-Al 2 O 3 single crystal) (0 0 0 1) substrates. These smooth substrates have 0.2-nm-high atomic steps and 60-80-nm-wide atomically flat terraces [19].…”

“…These smooth substrates have 0.2-nm-high atomic steps and 60-80-nm-wide atomically flat terraces [19]. Laser MBE has been intensively applied to grow epitaxial thin films of high-melting-point ceramics at relatively low substrate temperatures [13][14][15][16][17][18]. Recently, we fabricated highly oriented (1 0 0) LaB 6 polycrystalline thin films using ultrasmooth sapphire substrates [20].…”

Room-temperature synthesis of epitaxial oxide thin films for development of unequilibrium structure and novel electronic functionalization

“…15) Then, the buffer-enhanced epitaxial growth of ZnO film was examined using NiO buffer layer on the ultrasmooth sapphire (0001) 14) Further deposition of ZnO film (20 nm thick) was carried out on the NiO buffer layer (3 nm thick) at RT. From the viewpoint of crystal structure, it is of interest how the polarity of ZnO films changes depending on the growth temperature.…”