Abstract:Source oxidation of easily oxidizing elements such as Ca, Sr, Ba, and Ti in an oxidizing ambient leads to their flux instability and is one of the biggest problems in the multi-elemental oxide Molecular Beam Epitaxy technique. Here we report a new scheme that can completely eliminate the source oxidation problem: a self-gettering differential pump using the source itself as the pumping medium. The pump simply comprises a long collimator mounted in front of the source in extended port geometry. With this arrang… Show more
“…For Sr, if source oxidation is minimized by differential pumping and proper effusion-cell geometry design, PID control of the cell temperature can stabilize the Sr flux to within 1%, even when using an effusion cell. [73][74][75] In contrast, the high melting point of Ru, which must be deposited by e-beam, requires the supplied flux to be monitored in real-time and the measurements to be fed back to the e-beam power supply in order to keep it within 1%. 36,38,39) Real-time monitoring of Sr and Ru fluxes during e-beam evaporation has been performed using atomic absorption spectroscopy (AAS) 76,77) sensors and electron impact emission spectroscopy (EIES) 38,78) sensors (see Fig.…”
Section: Growth Methods Of Ultra-high-quality Sro Filmsmentioning
The itinerant 4d ferromagnetic perovskite SrRuO3 [bulk Curie temperature (TC) = 165 K] has been studied extensively for many decades because of the unique nature of its ferromagnetism, metallicity, chemical stability, and compatibility with other perovskite-structured oxides. Recently, SrRuO3 has been gathering renewed interest as a magnetic Weyl semimetal and a two-dimensional ferromagnetic system. Ultra-high-quality SrRuO3 film growth techniques, combining oxide molecular beam epitaxy technology and a statistical machine learning method, have revealed new physics and physical properties of SrRuO3 as a magnetic Weyl semimetal, such as quantum transport of Weyl fermions and high-mobility two-dimensional carriers from surface Fermi arcs. This review summarizes the methods of growing ultra-high-quality SrRuO3 films and novel physics found in them. In addition, progress in crystal structure analyses and the electrical and magnetic properties of SrRuO3 over the last decade will also be discussed.
“…For Sr, if source oxidation is minimized by differential pumping and proper effusion-cell geometry design, PID control of the cell temperature can stabilize the Sr flux to within 1%, even when using an effusion cell. [73][74][75] In contrast, the high melting point of Ru, which must be deposited by e-beam, requires the supplied flux to be monitored in real-time and the measurements to be fed back to the e-beam power supply in order to keep it within 1%. 36,38,39) Real-time monitoring of Sr and Ru fluxes during e-beam evaporation has been performed using atomic absorption spectroscopy (AAS) 76,77) sensors and electron impact emission spectroscopy (EIES) 38,78) sensors (see Fig.…”
Section: Growth Methods Of Ultra-high-quality Sro Filmsmentioning
The itinerant 4d ferromagnetic perovskite SrRuO3 [bulk Curie temperature (TC) = 165 K] has been studied extensively for many decades because of the unique nature of its ferromagnetism, metallicity, chemical stability, and compatibility with other perovskite-structured oxides. Recently, SrRuO3 has been gathering renewed interest as a magnetic Weyl semimetal and a two-dimensional ferromagnetic system. Ultra-high-quality SrRuO3 film growth techniques, combining oxide molecular beam epitaxy technology and a statistical machine learning method, have revealed new physics and physical properties of SrRuO3 as a magnetic Weyl semimetal, such as quantum transport of Weyl fermions and high-mobility two-dimensional carriers from surface Fermi arcs. This review summarizes the methods of growing ultra-high-quality SrRuO3 films and novel physics found in them. In addition, progress in crystal structure analyses and the electrical and magnetic properties of SrRuO3 over the last decade will also be discussed.
“…Sputtering and PLD utilize targets where the indirect control of deposition parameters makes stoichiometry control more challenging with increasing film growth rate. Conventional solid-source MBE growth for perovskite oxides requires precise calibration of the Sr and Ti fluxes, however, the level of oxygen pressure needed for high-growth rates adversely affect effusion cell flux stability due to unintentional oxidation of the source material in the crucible 31 , thus limiting this technique to low growth rates 16,17 and precluding it as a cost-effective production tool for virtual perovskite oxide substrates 17,32 .Fig. 1Growth rates and control of film stoichiometry.…”
The availability of native substrates is a cornerstone in the development of microelectronic technologies relying on epitaxial films. If native substrates are not available, virtual substrates - crystalline buffer layers epitaxially grown on a structurally dissimilar substrate - offer a solution. Realizing commercially viable virtual substrates requires the growth of high-quality films at high growth rates for large-scale production. We report the stoichiometric growth of SrTiO
3
exceeding 600 nm hr
−1
. This tenfold increase in growth rate compared to SrTiO
3
grown on silicon by conventional methods is enabled by a self-regulated growth window accessible in hybrid molecular beam epitaxy. Overcoming the materials integration challenge for complex oxides on silicon using virtual substrates opens a path to develop new electronic devices in the More than Moore era and silicon integrated quantum computation hardware.
“…One way to prevent source oxidation includes the use of crucible aperture to reduce the exposure to oxygen and/or differential pumping to maintain low oxygen partial pressure locally around the source. 113,114 Additionally, maintaining oxygen stoichiometry is non-trivial in an oxide MBE. Typically, oxygen pressure is limited to < 10 -5 Torr during film growth to prevent potential oxidation of various filaments/gauges and other parts of the MBE system.…”
Section: Challenges With Oxide Mbe Of Tin-based Compoundsmentioning
Perovskite oxides are ABO 3-type compounds with a crystal structure capable of accommodating a large number of elements at Aand B-sites. Owing to their flexible structure and complex chemistry, they exhibit a wide range of functionalities as well as novel ground states at the interface. However, in comparison with conventional semiconductors such as silicon, they possess orders of magnitude lower room-temperature electron mobilities limiting their room-temperature electronic applications. For example, in a prototypical doped SrTiO 3 , the room-temperature electron mobility remains below 10 cm 2 V-1 s-1 regardless of the defect minimization. Discovery of high room-temperature mobility in alkaline-earth stannates
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
