Formation of strontium template on Si(1 0 0) by atomic layer deposition

The formation of ordered Sr overlayers on Si(1 0 0) by Atomic Layer Deposition (ALD) from bis(triisopropylcyclopentadienyl) Strontium (Sr(C5iPr3H2)2) and H2O has been investigated. SrO overlayers were deposited on a 1-2 nm SiO2/Si(1 0 0) substrate, followed by a deoxidation process to remove the SiO2 layer at high temperatures. Auger electron spectroscopy, Rutherford backscattering spectrometry, spectroscopic ellipsometry, and low-energy electron diffraction were used to investigate the progress of both ALD and deoxidation processes. Results show that an ordered Sr/Si(1 0 0) surface with 2 × 1 pattern can be obtained after depositing several monolayers of SrO on Si using ALD followed by an anneal at 800-850 °C. The (2 × 1) ordered Sr/Si(1 0 0) surface is known to be an excellent template for the epitaxial growth of SrTiO3 (STO) oxide. The present results demonstrate that ALD is a potential alternative to molecular beam epitaxy methods for the fabrication of epitaxial oxides on semiconductor substrates.

Research highlights▶ Epitaxial template layers for crystalline oxide heteroepitaxy on silicon have been grown by ALD. ▶ Ordered reconstructions of Sr/Si monolayers have been achieved by ALD with oxide desorption. ▶ Carbonate free SrO growth was achieved by ALD with cyclopentadienyl Sr precursor and water reactants. ▶ Silicate layers are proposed as intermediates for the formation of the epitaxial Sr layers. ▶ The present results demonstrate that ALD is a potential alternative to molecular beam epitaxy methods for the fabrication of epitaxial oxides on semiconductor substrates.