Surface-controlled growth of LaAlO3 thin films by atomic layer epitaxy
Surface-controlled growth of LaAlO3 thin films by atomic layer epitaxy
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DOI：
10.1039/b102677c
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发表时间：
2001-01-01
影响因子：
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通讯作者：
Niinistö, L
中科院分区：
文献类型：
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作者：
Nieminen, M;Sajavaara, T;Niinistö, L
采用原子层外延法制备了β -二酮酸型前驱体La(thd)(3)和Al(acac)(3) LaAlO3薄膜。臭氧被用作氧气源。薄膜生长在碱石灰玻璃、Si（100）、mgo缓冲Si（100）、蓝宝石和SrTiO3（100）衬底上。在325 ~ 400℃的温度范围内，研究了La:Al前驱体脉冲比对薄膜生长和质量的影响。用RBS、TOF-ERDA和XPS测定了碳的化学计量学和杂质水平，并用FTIR鉴定了碳杂质的化学类型。用XRD和AFM分析了材料的结晶度和表面形貌。薄膜透明均匀，厚度可通过循环次数精确控制。沉积膜为无定形，900℃退火后变为结晶。在Si（100）和MgO（111）缓冲Si（100）衬底上生长的退火膜具有优先取向（110），而在MgO（100）缓冲Si（100）衬底上生长的退火膜具有优先取向（100）。在SrTiO3（100）表面900℃退火后获得了外延光滑的LaAlO3薄膜，并通过测量（200）反射的x射线摇摆曲线和AFM表面粗糙度进行了验证。化学计量LaAlO3膜所含
LaAlO3 thin films were deposited by atomic layer epitaxy (ALE) from beta -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), MgO-buffered Si(100), sapphire and SrTiO3(100) Substrates. The influence of the La:Al precursor pulsing ratio on the film growth and quality in the temperature range of 325-400 degreesC 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 degreesC. 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 LaAlO3 thin films were obtained on SrTiO3(100) after annealing at 900 degreesC, verified by measurement of the X-ray rocking curve of the (200) reflection and the AFM surface roughness. Stoichiometric LaAlO3 films contained