CONTEXT
Micro-transfer printing (μTP) is an emerging micro-assembly technique that enables the transfer of microstructures (semiconductors, optoelectronic components, passive circuits, etc.) from a donor substrate to a receiver substrate with high spatial precision. This technology is particularly well suited for heterogeneous integration, i.e., the assembly of highly dissimilar materials or components onto the same platform [1]. One of the key aspects of this technology lies in the preparation of the source substrate, particularly the sacrificial layer that enables the release of the component to be transferred.
Functional oxides, crystalline transition-metal oxides exhibiting numerous remarkable properties (ferroelectric, piezoelectric, ferromagnetic, electro-optic, thermoelectric, etc.), enable a wide range of key applications (low-power non-volatile memories, ultra-fast electro-optic modulators, ultra-sensitive sensors, actuators, coolers, generators, etc.). However, the deployment of functional oxide devices on industrial technological platforms remains limited due to several technological barriers. Most devices targeting these applications require, on the one hand, epitaxial thin films (with controlled crystalline orientation, often grown on specific single-crystal substrates that are not compatible with large-scale industrial production), and, on the other hand, micro-/nano-structured thin films (photonic, electronic, thermoelectric circuits, etc.).
To overcome these current limitations, one promising approach is the use of epitaxial water-soluble sacrificial oxide layers [2–6], which would enable, through micro-transfer printing (μTP), the release and transfer of micro-/nano-structured functional oxides onto a chosen technological substrate. In this way, advanced devices based on functional oxides could be fabricated. The ambition of this PhD project is to develop the first building blocks required to open up this innovative pathway.
OBJECTIVES
We aim to develop and demonstrate the generic feasibility of this innovative process by targeting functional oxide layers with a perovskite structure (general chemical formula ABO₃) and their transfer via μTP onto selected technological substrates for various applications in the fields of photonics (ferroelectric oxides) and energy (thermoelectric oxides). The proposed process, as well as the targeted objectives, are described below:
1. Growth by MBE of epitaxial water-soluble sacrificial oxide layers (e.g. SrO)
2. Epitaxial regrowth of functional oxides with a perovskite structure (e.g. BaTiO₃)
3. Release and transfer by micro-transfer printing (μTP) onto SOI or SiO₂/Si substrates
4. Fabrication of micro-devices based on integrated functional oxides
KNOW-HOW at INL:
- Epitaxial growth by MBE of SrO layers on SrTiO3(001) [7]
- Epitaxial growth by MBE of ferroelectric BaTiO3 layers [8]
- Epitaxial growth by MBE of thermoelectric Sr1-xLaxTiO3 layers [9]
- Release and transfer by μTP of interband cascade lasers on Si [10]
REFERENCES
[1] G. Roelkens et al., IEEE J. of Selected topics in quantum eln, 29, No 3 (2023); https://ieeexplore.ieee.org/document/9953528
[2] D. Lu et al., Nature Mater. 15, 1255 (2016) ; https://doi.org/10.1038/nmat4749
[3] D. Ji et al., Nature 570, 87 (2019) ; https://doi.org/10.1038/s41586-019-1255-7
[4] D. Pesquera et al., J. Phys. : Condens. Matter. 34, 383001 (2022) ; https://doi.org/10.1088/1361-648X/ac7dd5
[5] F.M. Chiabrera et al., Ann. Phys. 534, 9, 2200084 (2022) ; https://doi.org/10.1002/andp.202200084
[6] S. Varshney et al., ACS Nano 18, 8, 6348 (2024) ; https://doi.org/10.1021/acsnano.3c11192
[7] G. Delhaye, Thèse de doctorat, ECL (2006) ; https://theses.fr/2006ECDL0045
[8] L. Mazet et al., J. Appl. Phys. 116, 214102 (2014) ; https://doi.org/10.1063/1.4902165
[9] M. Apreutesei et al., Sci. Technol. Adv. Mater. 18, 430 (2017); https://doi.org/10.1080/14686996.2017.1336055
[10] Y. Billiet et al., Advanced Photonics Congress (2025); https://doi.org/10.1364/IPRSN.2025.ITh3B.5
