Epitaxial Growth of SrRuO₃Thin Film Electrode on Si by Pulsed Laser Deposition

Abstract

Pseudocubic SrRuO 3 (100) epitaxial thin films were fabricated on Si (100) with a SrO buffer layer by pulsed laser deposition (PLD). Reflection high-energy electron diffraction (RHEED) revealed that the SrO layer is epitaxially grown on naturally oxidized Si substrates with an orientation relationship of SrO (110)/Si (100) and SrO 001 //Si 011 . Subsequent SrRuO 3 deposition resulted in a (100) epitaxial thin film possessing good crystallinity with a full-width at half maximum (FWHM) of 1.9 • in the SrRuO 3 (200) rocking curve by X-ray diffraction (XRD). Based on the Gibbs free energy change in the reaction of silicon with alkaline earth metal oxides, deoxidization of SiO 2 on Si by Sr is thought to play an important role in the epitaxial growth of SrO. Cross-sectional observation for the optimized SrRuO 3 /SrO/Si sample using transmission electron microscopy (TEM) revealed that the thickness of the SrO layer is less than 2 nm and that the SrRuO 3 electrode forms an epitaxial thin film almost directly on Si.

Simultaneous heteroepitaxial growth of SrO (001) and SrO (111) during strontium-assisted deoxidation of the Si (001) surface

“…TEM analysis has revealed a 6 nm-thick SrO lm on top of amorphous Si-oxide layer, with orientation SrO (110)kSi (100) and SrO h001ikSi h011i. 39 Noteworthy, the stability of this pattern is thickness dependent: 50 nm thick SrO on Si was grown in "cube-on-cube" manner i.e. In the case of our samples, the layer structure observed by TEM is the same for all three routes, with main difference in their thickness.…”

“…57 In Chen et al and Higuchi et al studies the SrO has been used both as buffer layer and deoxidizing agent. 39,58,59 It was observed that during heating of thin SrO layer on Si/SiO 2 a characteristic RHEED pattern is formed, however, only at certain temperature ($700 C). TEM analysis has revealed a 6 nm-thick SrO lm on top of amorphous Si-oxide layer, with orientation SrO (110)kSi (100) and SrO h001ikSi h011i.…”

“…Higuchi et al have shown that epitaxial orientation of SrO to silicon can be described as SrO (110)kSi (100) and SrO h001ikSi h011i. 39 Also, it was found that this epitaxial orientation was thickness dependent. Besides, the same study reported additional transmission spots the origin of which was not discussed by authors.…”

“…38 In Higuchi et al study TEM analysis has revealed a 6 nm-thick SrO lm on top of amorphous Si-oxide layer, with orientation SrO (110)kSi (100) and SrO [001]kSi [011]. 39 Noteworthy, the stability of this pattern is thickness dependent: 50 nm thick SrO on Si was grown in a "cube-on-cube" manner i.e. SrO (100)kSi (100) and SrO [011]k Si [011].…”

Structural and dielectric properties of epitaxial Ba0.6Sr0.4TiO3 thin films grown on Si substrates with thin SrO buffer layers

“…A dc bias voltage was applied to the device through external bias tees in order to protect the network analyzer. orientation may be promoted as a consequence of the structural match between SrO and the Si substrate with a small misfit of −5.5% along the SrO <010>//Si <010> in SrO (100)//Si (100) [11]. As the oxygen pressure was decreased from 1×10 −5 to 6×10 −6 Torr, the intensities of the SrO (200) diffraction peaks slightly increased.…”