Thin-film devices play an increasingly larger role in society. From processor chips to solar panels and anti-freeze window coatings: all such devices rely on depositing a material of choice on a suitable substrate. All functional materials consist of one or more elements from the periodic table. Ideally, materials physicists can use any combination of those elements to create materials with new functionalities. In practice however, not all elements can be deposited by a single conventional technique such as sputtering or thermal evaporation. For example, the required temperature for evaporation could be too high for the crucible holding the material.

Within the department of Solid-State Quantum Electronics, we recently developed a new technique for the synthesis of thin films. This technique, thermal laser epitaxy (TLE), makes use of high-power lasers to locally heat a source material, keeping the surroundings relatively cold. We have shown that TLE can evaporate any practical element in the periodic table. Compound materials can be realized by using multiple lasers. Moreover, all of this can be done in any gas environment because laser beams propagate through any transparent medium. These properties makes TLE a promising technique to grow films of previously inaccessible materials, but also to do so on an industrial scale.

For all such applications, the behavior of the source material during evaporation is a key ingredient. The project will focus on this topic, aimed towards understanding the evaporation process in detail and optimizing it accordingly.

The student will work in a diverse team of scientists and engineers, with a large degree of freedom to engage in various tasks within the team. Because TLE is a newly developed technique, we expect new challenges to emerge as the project progresses. Likewise, currently investigated challenges may have been resolved before the start of the project. Possible activities of the student within the project include, but certainly are not limited to: experimental investigations of film deposition, laser heating of exotic substrates, evaporation in a reactive background gas, high-precision epitaxy, epitaxy of refractory materials, temporal and spatial stability in controlling the process, scaling to large substrate areas and high throughput, numerical modeling of evaporation dynamics, and proof-of-concept investigations of new, out-of-the-box ideas that come up as the project progresses.

Figure:
Schematic of the interior of a TLE deposition chamber. One or multiple heating lasers heat one or multiple elemental sources, which evaporate towards a laser-heated substrate.
 
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