Research Update: Van-der-Waals epitaxy of layered chalcogenide Sb2Te3 thin films grown by pulsed laser deposition

“…Therefore 600 K is the highest practical growth temperature for Sb 2 Te 3 using quasi-equilibrium deposition methods, such as MBE. This low sticking coefficient may also explain some of the non-stoichiometric films reported recently in the literature [32,33] and the lower growth rates at temperatures above 533 K [35]. Figure 6(b) depicts the case where the substrate temperature is too high, and there is no seed layer.…”

Section: Discussionmentioning

confidence: 62%

“…Moreover, understanding these dependencies might help to explain why different research groups seem to grow different crystals despite their growth temperatures being similar. For example, there are some reports that the sputter grown Sb 2 Te 3 is actually Te deficient [32,33], whilst other groups do not see this effect, and there are even reports that high quality Sb 2 Te 3 can be grown at temperatures as low as 140 • C while other reports show that temperatures as high as 300 • C are necessary [13,35]. Boschker and Calarco discussed the differences between sputtering, PLD and MBE for Ge 2 Sb 2 Te 5 fabrication, but the origin of these differences is unclear [41].…”

Section: Introductionmentioning

confidence: 99%

Differences in Sb <sub>2</sub>Te <sub>3</sub> Growth by Pulsed Laser and Sputter Deposition

et al. 2020

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High quality van der Waals chalcogenides are important for phase change data storage, thermoelectrics, and spintronics. Using a combination of statistical design of experiments and density functional theory, we clarify how the out-ofequilibrium van der Waals epitaxial deposition methods can improve the crystal quality of Sb 2 Te 3 films. We compare films grown by radio frequency sputtering and pulsed laser deposition (PLD). The growth factors that influence the crystal quality for each method are different. For PLD grown films a thin amorphous Sb 2 Te 3 seed layer most significantly influences the crystal quality. In contrast, the crystalline quality of films grown by sputtering is rather sensitive to the deposition temperature and less affected by the presence of a seed layer. This difference is somewhat surprising as both methods are out-of-thermal-equilibrium plasma-based methods. Non-adiabatic quantum molecular dynamics simulations show that this difference originates from the density of excited atoms in the plasma. The PLD plasma is more intense and with higher energy than that used in sputtering, and this increases the electronic temperature of the deposited atoms, which concomitantly increases the adatom diffusion lengths in PLD. In contrast, the adatom diffusivity is dominated by the thermal temperature for sputter grown films. These results explain the wide range of Sb 2 Te 3 and superlattice crystal qualities observed in the literature. These results indicate that, contrary to popular belief, plasma-based deposition methods are suitable for growing high quality crystalline chalcogenides.

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“…It should be noted that RHEED is well established for PLD, but not for sputtering. Recently, RHEED has been used to study the growth of Sb 2 Te 3 grown by PLD [41], indicating that it can also be used for other GST compositions during PLD. Finally, the possibility to use separated sources for the constituents in MBE instead of a single compound target as in PLD or sputtering leads to different growth kinetics.…”

Section: Physical Deposition Methodsmentioning

confidence: 99%

Growth of crystalline phase change materials by physical deposition methods

Boschker

Calarco

2017

Advances in Physics: X

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Phase change materials are a technologically important mate rials class and are used for data storage in rewritable DVDs and in phase change random access memory. Furthermore, new applications for phase change materials are emerging. Phase change materials with a high structural quality, such as offered by epitaxial films, are needed in order to study the fundamental properties of phase change materials and to improve our understanding of this materials class. Here, we review the progress made in the growth of crystalline phase change materials by physical methods, such as molecular beam epitaxy, sputtering, and pulsed laser deposition. First, we discuss the difference and similarities between these physical deposition methods and the crystal structures of Ge 2 Sb 2 Te 5 , the prototype phase change material. Next, we focus on the growth of epitiaxial GST films on (0` 0 1) and (1 1 1)oriented substrates, leading to the conclusion that (1 1 1)oriented substrates are preferred for the growth of phase change materials. Finally, the growth of GeTe/Sb 2 Te 3 superlattices on amorphous and single crystalline substrates is discussed.

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Research Update: Van-der-Waals epitaxy of layered chalcogenide Sb2Te3 thin films grown by pulsed laser deposition

Cited by 43 publications

References 40 publications

Phase change thin films for non-volatile memory applications

Phase change thin films for non-volatile memory applications

Differences in Sb <sub>2</sub>Te <sub>3</sub> Growth by Pulsed Laser and Sputter Deposition

Growth of crystalline phase change materials by physical deposition methods

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