Heating c-plane sapphire to a temperature of 1700 °C results in a perfect surface for subsequent epitaxy. These surfaces are characterized by atomically flat double-stepped terraces with widths exceeding 1 μm. The atoms on the surface rearrange in a singular in-plane orientation of the (√31x√31)R9° surface reconstruction, as shown in the reflection high-energy electron diffraction (RHEED) image on the right. The observation of up to 20 Laue circles indicates the high crystal quality of the surface.
Evaporation of All Elements
We have explored the deposition of elemental metal films with TLE. So far we have succeeded in depositing films with thicknesses ranging from 1 to 500 nm on 2 inch Si wafers. All elemental sources could be evaporated in the same setup with growth rates between 0.01 and 1 Å/s by varying the laser power. Due to the inherent efficiency of the TLE process, significantly less power is required compared to high-temperature effusion cells and e-beam evaporators. A set of sample examples is shown below. The films are dense and homogeneous and have a very smooth surface morphology. These results show that laser evaporation is well-suited for the growth of complex compounds with excellent control.
An overview of the key scientific publications about thermal laser epitaxy.
2019-05 / AIP Advances 9: Film deposition by thermal laser evaporation
2020-03 / APL Materials 8: In situ thermal preparation of oxide surfaces
2021-02 / Journal of Laser Applications 33: Thermal laser evaporation of elements from across the periodic table
2021-08 / APL Materials 9: Thermal laser evaporation for the growth of oxide films
2021-08 / Journal of Vacuum Science & Technology A 39: Epitaxial film growth by thermal laser evaporation
2022-09 / Thin Solid Films 758: Ultrasmooth graphene-coated metal thin films on sapphire grown by thermal laser epitaxy
2022-12 / Journal of Applied Physics 132: Thermal laser evaporation of elemental metal sources in oxygen
2023-01 / Advanced Materials 35: Self-Assembly of Nanocrystalline Structures from Freestanding Oxide Membranes
2023-05 / Journal of Vacuum Science & Technology A 41: Why thermal laser epitaxy aluminum sources yield reproducible fluxes in oxidizing environments
2023-10 / Crystal Growth and Design 23: Thermal Laser Epitaxy of Carbon Films