Periodic Reporting for period 3 - XFab (Xene Fabrication for a Two-Dimensional Nanotechnology Platform)
Período documentado: 2021-04-01 hasta 2022-09-30
The XFab projects stems from the idea of exploiting the capability to grow two-dimensional (2D) Xenes and lift them to a higher technology level than the lab demonstration. Xenes are the last frontier of 2D materials made of a single element (like graphene) and displaying diverse electronic states (beyond graphene). Not all the Xene systems are suitable for this technology upgrade because they often suffer from scalability and stability issues, or they may be stacked in a configuration that is unfit to device integration. Often, Xenes currently remain confined to a niche research where the atomistic identification or the demonstration of specific, though important, physical properties are the main target. XFab is the first step to cast Xenes away from this academic perspective towards a technology exploitation.
The societal challenges in the future technologies spanning from the digital agenda (e.g. 5G transition, internet of things, etc.), green economy (renewable energy sources, etc.) as well ass long-standing background challenges such as the technology evolution of electronic devices and the emerging request for energy conversion and storage are in direct need of new materials that are able to more effectively boost the mainstream technology performance or to open new paradigms of operation. This was the case of graphene that just from its rise radically upset the current thinking of mainstream technologies opening up new paths in nanotechnologies. Xenes may expand the technology potential of graphene and then boost the existing technology background or pave the way to new ones.
Few examples may clarify the opportunity. Making silicene fit to electronic devices would ultimately downscale the device feature size and hence reduce the overall power consumption. Making stanene fit to a topological transistor may reset the energy dissipation by taking benefit from the unique predicted topological properties. Out of the nanoelectronics framework, silicene may also be adapted to work as electrode in Li-ion batteries, or as an active materials in THz plasmonic grating with outstanding implications in the silicon photonics. Epitaxial phosphorene can provide the very first one-atom thick 2D semiconductor available for nanoelectronics, optoelectronics, and sensors.
As overall objectives, here we want to select those Xenes that can have a true potential for device integration in nanotechnology taking the electronic device as prior vehicle in this direction but also considering other technology directions like photonics, energy, etc. where the Xenes may bring to a solid advance. Therefore main objectives go through a) the selection of those Xenes that are reliable in making the technology step, b) the development of Xene integration schemes in operational devices (electronic devices like transistors and/or memristors, but also optical devices like plasmonic gratings, and more), and c) the proof of Xene device operation.
The societal challenges in the future technologies spanning from the digital agenda (e.g. 5G transition, internet of things, etc.), green economy (renewable energy sources, etc.) as well ass long-standing background challenges such as the technology evolution of electronic devices and the emerging request for energy conversion and storage are in direct need of new materials that are able to more effectively boost the mainstream technology performance or to open new paradigms of operation. This was the case of graphene that just from its rise radically upset the current thinking of mainstream technologies opening up new paths in nanotechnologies. Xenes may expand the technology potential of graphene and then boost the existing technology background or pave the way to new ones.
Few examples may clarify the opportunity. Making silicene fit to electronic devices would ultimately downscale the device feature size and hence reduce the overall power consumption. Making stanene fit to a topological transistor may reset the energy dissipation by taking benefit from the unique predicted topological properties. Out of the nanoelectronics framework, silicene may also be adapted to work as electrode in Li-ion batteries, or as an active materials in THz plasmonic grating with outstanding implications in the silicon photonics. Epitaxial phosphorene can provide the very first one-atom thick 2D semiconductor available for nanoelectronics, optoelectronics, and sensors.
As overall objectives, here we want to select those Xenes that can have a true potential for device integration in nanotechnology taking the electronic device as prior vehicle in this direction but also considering other technology directions like photonics, energy, etc. where the Xenes may bring to a solid advance. Therefore main objectives go through a) the selection of those Xenes that are reliable in making the technology step, b) the development of Xene integration schemes in operational devices (electronic devices like transistors and/or memristors, but also optical devices like plasmonic gratings, and more), and c) the proof of Xene device operation.
The workflow up to now has been articulated according to the project implementation plan in the three declared work packages WP, WP1: Synthesis of Xene Systems, WP2: Stabilization and device integration, WP3: Physical Characterization. General aspects on the workflow are as follows. According to the scientific plan, a brand new MBE apparatus has been regularly installed and set-up after a 18 months-long purchase procedure. WP3 has paralleled all the WP1 steps but the declared acquisition of an in situ spectroscopy tool has been delayed to the second half of the project (namely 2021) in order to give the priority to the team consolidation. In detail, specific aspects of the workflow are as follows.
WP1 has been carried out in a pre-existing MBE apparatus endowed with in situ XPS and STM tools, and more recently (since October 2019 on) on the new MBE apparatus too.Specific achievements are listed as follows:
- Silicene grown on sapphire substrates as single- and multi-layer; large-area silicene grown Ag substrate for further processing ( WP2); epitaxial phosphorene grown on Au substrates and stanene grown on Ag substrates;
- silicene-stanene and stanene-silicene heterostructures proven on Ag substrates;
- functionalization of Xenes in terms of intercalation through other 2D layer (work-in-progress).
WP2 has been carried out by extending previously developed stabilization schemes to new Xenes produced in WP1 and by developing new schemes for processing Xenes and transferring them from their native substrates to a second substrate. Specific achievements are listed as follows:
- Al2O3 encapsulation applied to epitaxial phosphorene and stanene;
- silicene transfer performed via wet and dry transfer methodologies.
WP3 has been carried out by means of in situ probing (XPS, STM, LEED-Auger that will include in situ Raman spectroscopy shortly). Specific achievements are listed as follows:
- in situ characterization of silicene-on-sapphire (XPS), epitaxial phosphorene (STM-STS and XPS); alpha-Sn on InSb substrates (XPS and STM); silicene, stanene, and heterostructures (LEED-Auger probing); ex situ characterization of Xene systems by micro-Raman spectroscopy with varying excitation wavelengths.
Gain results are as follows:
- Epitaxy of silicene on sapphire and its optical conductivity [Grazianetti et al, Nano Lett. (2018) 18, 7124];
- Growth of epitaxial phosphorene on Au-based substrates [Grazianetti et al, Nanosc. (2019) 11, 18232];
- Evidence of stanene in the tin epitaxy on sapphire [ Grazianetti et al, submitted] and of -Sn (stanene-like) in InSb substrates;
- Extension of the Al2O3 encapsulation to Xenes-on-substrates [ Molle et al, Faraday Discussion 2020, https://doi.org/10.1039/C9FD00121B];
- New disassembling and transfer schemes for Xenes from their native substrate [ Martella et al, Adv. Funct. Mater. (2020), 30, 2004546];
- Growth of antimonene nanosheets by metal organic chemical vapor deposition (cooperative seed activity in the HI).
In parallel, a significant amount of work was devoted to analyse the current state of the art and give new perspectives about the Xenes [Molle et al, Chem Soc Rev (2018) 47, 6370; Molle and Grazianetti, Research (AAAS) 2019, 8494606 (2019); Grazianetti et al, PSS-RRL (2019), 14, 1900439].
WP1 has been carried out in a pre-existing MBE apparatus endowed with in situ XPS and STM tools, and more recently (since October 2019 on) on the new MBE apparatus too.Specific achievements are listed as follows:
- Silicene grown on sapphire substrates as single- and multi-layer; large-area silicene grown Ag substrate for further processing ( WP2); epitaxial phosphorene grown on Au substrates and stanene grown on Ag substrates;
- silicene-stanene and stanene-silicene heterostructures proven on Ag substrates;
- functionalization of Xenes in terms of intercalation through other 2D layer (work-in-progress).
WP2 has been carried out by extending previously developed stabilization schemes to new Xenes produced in WP1 and by developing new schemes for processing Xenes and transferring them from their native substrates to a second substrate. Specific achievements are listed as follows:
- Al2O3 encapsulation applied to epitaxial phosphorene and stanene;
- silicene transfer performed via wet and dry transfer methodologies.
WP3 has been carried out by means of in situ probing (XPS, STM, LEED-Auger that will include in situ Raman spectroscopy shortly). Specific achievements are listed as follows:
- in situ characterization of silicene-on-sapphire (XPS), epitaxial phosphorene (STM-STS and XPS); alpha-Sn on InSb substrates (XPS and STM); silicene, stanene, and heterostructures (LEED-Auger probing); ex situ characterization of Xene systems by micro-Raman spectroscopy with varying excitation wavelengths.
Gain results are as follows:
- Epitaxy of silicene on sapphire and its optical conductivity [Grazianetti et al, Nano Lett. (2018) 18, 7124];
- Growth of epitaxial phosphorene on Au-based substrates [Grazianetti et al, Nanosc. (2019) 11, 18232];
- Evidence of stanene in the tin epitaxy on sapphire [ Grazianetti et al, submitted] and of -Sn (stanene-like) in InSb substrates;
- Extension of the Al2O3 encapsulation to Xenes-on-substrates [ Molle et al, Faraday Discussion 2020, https://doi.org/10.1039/C9FD00121B];
- New disassembling and transfer schemes for Xenes from their native substrate [ Martella et al, Adv. Funct. Mater. (2020), 30, 2004546];
- Growth of antimonene nanosheets by metal organic chemical vapor deposition (cooperative seed activity in the HI).
In parallel, a significant amount of work was devoted to analyse the current state of the art and give new perspectives about the Xenes [Molle et al, Chem Soc Rev (2018) 47, 6370; Molle and Grazianetti, Research (AAAS) 2019, 8494606 (2019); Grazianetti et al, PSS-RRL (2019), 14, 1900439].
The achievements of the XFab project beyond the state of the art include:
1- Prior demonstration of Xene (silicene and stanene) epitaxy on sapphire;
2- First demonstration of universal Al2O3 encapsulation of epitaxial Xenes: silicene, epitaxial phosphorene, stanene proven, extension to other Xenes possible;
3- First demonstration of two possible Xene disassembling schemes and transfer to a second arbitrary substrates: t-UXEDO (transfer universal Xene encapsulation, decoupling and operation) and s-SEDNE (seamless silicene encapsulated delamination with native electrode)
Follow-ups of the activity till the end of the project will bring expected results on the following aspects:
1- Prior demonstration of Xene heterostructures;
2- Verification of silicene intercalation through other 2D layers as an effective way to functionalize the silicene;
3- Fabrication of operational electronic devices (namely field effect transistors and/or memristors) based on transferred/encapsulated Xenes or Xene heterostructures or Xenes directly grown on substrates;
4- Verification of plasmonic gratings based on Xenes on sapphire with field effect modulation.
1- Prior demonstration of Xene (silicene and stanene) epitaxy on sapphire;
2- First demonstration of universal Al2O3 encapsulation of epitaxial Xenes: silicene, epitaxial phosphorene, stanene proven, extension to other Xenes possible;
3- First demonstration of two possible Xene disassembling schemes and transfer to a second arbitrary substrates: t-UXEDO (transfer universal Xene encapsulation, decoupling and operation) and s-SEDNE (seamless silicene encapsulated delamination with native electrode)
Follow-ups of the activity till the end of the project will bring expected results on the following aspects:
1- Prior demonstration of Xene heterostructures;
2- Verification of silicene intercalation through other 2D layers as an effective way to functionalize the silicene;
3- Fabrication of operational electronic devices (namely field effect transistors and/or memristors) based on transferred/encapsulated Xenes or Xene heterostructures or Xenes directly grown on substrates;
4- Verification of plasmonic gratings based on Xenes on sapphire with field effect modulation.