Surface-controlled growth of LaAlO3 thin films by atomic layer epitaxy

Abstract

LaAlO 3 thin films were deposited by atomic layer epitaxy (ALE) from b-diketonate-type precursors La(thd) 3 and Al(acac) 3 . Ozone was used as an oxygen source. Films were grown on soda lime glass, Si(100), MgObuffered Si(100), sapphire and SrTiO 3 (100) substrates. The influence of the La : Al precursor pulsing ratio on the film growth and quality in the temperature range of 325-400 uC was studied in detail. Stoichiometry and impurity levels were measured using RBS, TOF-ERDA and XPS while the chemical type of carbon impurity was identified by FTIR. XRD and AFM were used to determine crystallinity and surface morphology. The films were transparent and uniform and their thickness could be accurately controlled by the number of deposition cycles. The as-deposited films were amorphous but became crystalline upon annealing at 900 uC. The annealed films grown on Si(100) and MgO(111)-buffered Si(100) substrates had a preferred (110) orientation whereas those grown on MgO(100)-buffered Si(100) substrates showed a preferred (100) orientation. Epitaxial and smooth LaAlO 3 thin films were obtained on SrTiO 3 (100) after annealing at 900 uC, verified by measurement of the X-ray rocking curve of the ( 200) reflection and the AFM surface roughness. Stoichiometric LaAlO 3 films contained v1.9 atom% carbon and about 0.3 atom% hydrogen as impurities.

Synthesis and characterization of lanthanum monoaluminate by co-precipitation method

“…Li et al [17] have used La (NO 3 ) 3 and Al (NO 3 ) 3 as raw materials and kept pH about at 9 in the coprecipitation method. Pure LaAlO 3 powders have been obtained after 00016-p. 6 calcined at 700 •C for 32 h or 800 •C for 2 h using hydroxide, cyanide and nitrate solid solution precursors as the starting materials. The appearance of LaAlO 3 is observed when calcined at 947 •C for12 h in air, as reported by Vidyasagar et al [18].…”

“…Lanthanum aluminate (LaAlO 3 ) has attracted a great attention in recent years because of its variety of applications [1][2][3][4][5][6][7][8]. LaAlO 3 with a perovskite-type structure [9] is widely used as substrates and electrically insulating buffers for depositing high-temperature superconducting films due to its high quality factor and excellent lattice and thermal expansion matching ability [2,6].…”

“…LaAlO 3 with a perovskite-type structure [9] is widely used as substrates and electrically insulating buffers for depositing high-temperature superconducting films due to its high quality factor and excellent lattice and thermal expansion matching ability [2,6]. Its use as a gate dielectric material has also been explored [10,11] .In addition, LaAlO 3 powder has been studied as a catalyst for oxidative coupling of methane and hydrogenation and hydrogenolysis of hydrocarbons due to its high catalytic activity [12].Polycrystalline LaAlO 3 has been commonly prepared by a solidstate reaction method: i.e.…”

MOCVD of LaAlO3 Films from a Molten Precursor Mixture: Characterization of Liquid, Gas, and Deposited Phases

“…[11] In addition, LaAlO 3 films were grown on MgO-buffered Si(100) and SrTiO 3 (100) substrates by atomic layer epitaxy (ALE). [12] As far as we know, our ªsimpleº MOCVD approach to the deposition of heteroepitaxial LaAlO 3 (100) films on SrTiO 3 (100) is still unique. [13] The key point of our process relies upon the application of a molten precursor mixture for both lanthanum and aluminum components.…”

Effects of Low Temperature O2 Treatment on the Electrical Characteristics of Amorphous LaAlO3 Films by Atomic Layer Deposition

“…It has a high dielectric constant (κ bulk is 20-25) (3, 4) as compared to SiO 2 (κ~3.9), wide band gap (E g =5.8 eV), high band offsets with respect to silicon (>2 eV) (5,6) and abrupt interfaces when grown on silicon (7,8). Many studies have shown that it is thermally stable in contact with silicon up to ~ 800 o C (9)(10)(11)(12).…”