Periodic Reporting for period 1 - NeGeMat (New Germaniun-based materials for Green electronics)
Okres sprawozdawczy: 2022-07-01 do 2024-06-30
NeGeMat aims to bring 2 new materials formed of earth-abundant and non (or low) toxicity elements to the realm of electronic devices. Many devices depend on scarce or toxic elements, for example most IR detectors used nowadays (motion detection, night vision, etc...) are based on MCT, which stands for mercury cadmium telluride, which are highly toxic and scarce. Bringing the possibility of new materials for fabrication of devices with more abundant elements can also reduce the need for elements mined in countries involved in conflicts for mining of minerals.
To achieve this, the project uses computational and experimental lab work to fabricate thin films (the needed architecture for fabrication of devices) of two materials, Sr3GeO and Sr2MnGe2O7. Sr3GeO is a narrow bandgap semiconductor which could be used for IR sensing applications, while Sr2MnGe2O7 has been predicted to be a Weyl semimetal, a new type of topologically non-trivial material that would bring new possibilities for the fabrication of new devices.
The project uses a combination of ab-initio calculations (density functional theory or DFT) together with thermodynamic calculations using the CALculation of PHAse Diagrams (CALPHAD) framework to predict the best conditions of temperature, pressure, etc... for the synthesis of thin films of these two materials by molecular beam epitaxy (MBE). This approach also reduces the waste created in trials without a clear guidance from such a strong modelling prior to the experimental synthesis of the materials.
To achieve this, the project uses computational and experimental lab work to fabricate thin films (the needed architecture for fabrication of devices) of two materials, Sr3GeO and Sr2MnGe2O7. Sr3GeO is a narrow bandgap semiconductor which could be used for IR sensing applications, while Sr2MnGe2O7 has been predicted to be a Weyl semimetal, a new type of topologically non-trivial material that would bring new possibilities for the fabrication of new devices.
The project uses a combination of ab-initio calculations (density functional theory or DFT) together with thermodynamic calculations using the CALculation of PHAse Diagrams (CALPHAD) framework to predict the best conditions of temperature, pressure, etc... for the synthesis of thin films of these two materials by molecular beam epitaxy (MBE). This approach also reduces the waste created in trials without a clear guidance from such a strong modelling prior to the experimental synthesis of the materials.
Absorption-controlled growth windows for both materials by MBE were identified though the use of DFT and CALPHAD calculations, one of the main objectives of this work.
Thin films of Sr3GeO were synthesized and preliminarily characterized, showing a narrow bandgap and X-ray diffraction peaks in agreement with the structure of the material.
Thin films of Sr3GeO were synthesized and preliminarily characterized, showing a narrow bandgap and X-ray diffraction peaks in agreement with the structure of the material.
The identification of an adsorption-controlled growth window for both Sr3GeO and Sr2MnGe2O7 proves that these materials are great candidates to be synthesized by MBE, which is not trivial. Particularly, the use of a hybrid effusion source for Sr3GeO in using a mix of Ge and GeO2 to obtain the right composition in the gas phase that can then lead to this adsorption-controlled growth is also an interesting result that can be transferred for the use in other materials, for example other Ge containing oxides.
The synthesis of thin films of Sr3GeO by use of a hybrid source is also a world-first as far as the participants in the project are aware, and can lead to great impact in new research using such a type of sources. Furthermore, this material is isostructural with Sr3SnO, which is a topological insulator, and the alloying of these materials could lead to interesting properties.
The synthesis of the Sr2MnGe2O7 requires more research, particularly challenging seems to be the mellilite structure it presents, with no commercially available substrates that share it and therefore finding a good match for epitaxy particularly difficult.
Further research is also required for Sr3GeO in order to better understand the properties and the effect of synthesis conditions on them.
The synthesis of thin films of Sr3GeO by use of a hybrid source is also a world-first as far as the participants in the project are aware, and can lead to great impact in new research using such a type of sources. Furthermore, this material is isostructural with Sr3SnO, which is a topological insulator, and the alloying of these materials could lead to interesting properties.
The synthesis of the Sr2MnGe2O7 requires more research, particularly challenging seems to be the mellilite structure it presents, with no commercially available substrates that share it and therefore finding a good match for epitaxy particularly difficult.
Further research is also required for Sr3GeO in order to better understand the properties and the effect of synthesis conditions on them.