Next Generation Epitaxy

Thermal laser epitaxy

STRATOLAS is a complete epitaxy system that is specifically designed and optimized for TLE. This allows for a small chamber design with a minimum number of parts inside the vacuum space. The system is equipped with our CO₂ laser substrate heater and can handle up to 5 different elemental sources.

Unique features

Universal compatibility across the entire periodic table on every source position

Local source heating for ultrapure epitaxy

THERMALAS substrate heating up to >2000 ℃

Broad compatibility with process gasses (O₃, O₂, N₂, NH₃) up to 10⁻² mbar

Rapid source material exchange without breaking the vacuum.

Real time process monitoring with RHEED

Small and fast loadlock, UHV storage

Class 1 laser safety

Class 1 qualification: hermetically sealed system, integrated water cooling and safety interlocks

Process monitoring using cameras

THERMALAS

Laser substrate heating

With THERMALAS, substrate heating takes minutes instead of hours. It gives you higher temperatures and faster ramp up/down rates. For low temperatures, it’s better than others. For high temperature, it’s the only choice.

You can use our THERMALAS substrate heater to upgrade your existing PLD or Sputter vacuum chamber. And you can use it later as a core component for our STRATOLAS TLE system.

Overview

Laser heating enables high substrate temperatures in an ultraclean environment. Our solution ensures light is absorbed well by all common substrate materials. It also minimizes contamination of the substrates, e.g. from glues or metal contacts.

Furthermore, extremely high temperatures and fast ramp rates are possible because only the substrate is heated. The substrate holder always remains much colder than the substrate because the absorption of our laser light by metals is small. The figure above shows an example of a sapphire crystal at T = 1700 ℃.

Access to higher temperatures allows for rapid thermal preparation of well-defined oxide surfaces in situ prior to growth, obviating the need for arduous chemical etching and improving throughput.

· Access substrate temperatures up to >2000 ℃ and ramp rates up to 400 ℃/s

· Tight PID control with an on-axis pyrometer over a dynamic range of more than 3 orders of magnitude

· Local heating minimizes outgassing

· Thermal preparation of terminated, growth-ready surfaces in minutes

· THERMALAS-A

Our most rugged and versatile design. Includes adaptive optical elements for electronic control of the incident beam profile to ensure highest possible thermal uniformity across the substrate.

· THERMALAS-S

Features a more compact optical design, with fewer beam shaping components generating a static top-hat beam profile. Available at competitive entry-level pricing.

· Available as add-on upgrade for existing epitaxy systems

· Substrate sizes from 5x5 mm2 up to 100 mm

· Hermetically closed laser beamline and interlock for Class 1 safety rating

The main challenges in the epitaxy of binary transition metal nitrides are the high substrate temperatures and the strong nitriding atmospheres required. The laser heating processes at the core of TLE are compatible with high NH3 background pressures. This enables high growth rates and yields nitride films of extremely high quality

This work was recently published in Applied Physics Letters Materials.

The figure shows secondary ion mass spectrometry data of a homoepitaxial sapphire film grown by thermal laser epitaxy. The data reveal a lower level of impurities in the film compared to the substrate. This demonstrates the potential of TLE to realize ultraclean heterostructures.

This work was recently published in Applied Physics Letters Materials.

Two recent publications find great benefits in using thermal laser epitaxy for the growth of high-quality epitaxial ruthenium and tantalum films. TLE enables the evaporation of these elements in extremely clean environments and the high substrate temperatures during the growth and or post-annealing result in films with high structural coherence. The image shows a cross-section of a ruthenium layer without any discernible surface and interface roughness.

The graph shows a pole figure of a heterostructure with a symmetry-forbidden interface. The square lattice of SrTiO3 is bonded to the hexagonal lattice of sapphire. The direct bonding without the presence of a contamination layer was achieved by first annealing the sapphire surface at extreme temperature with a CO2 laser heating system, subsequently transferring a SrTiO3 membrane and finally annealing the heterostructure to form the interface.   

This work was recently published in Advanced Materials.

The main challenges for the epitaxy of high-quality oxide layers are identified as the high oxidization potentials needed to achieve many desired compounds, the high temperatures required for numerous oxide phases to form, and the high temperatures necessary to grow films in adsorption-controlled growth modes. To overcome these challenges, various possibilities exist. Thermal laser epitaxy and CO2 laser heaters are deemed especially promising in this regard, because with this technology growth in extreme environments is possible.

This work was recently published in Applied Physics Letters Materials.

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.

This work was recently published in Advanced Materials.

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.

Oxide substrate surfaces can be prepared simply by high-temperature annealing in the growth chamber. This removes the need for chemical treatments and ex situ annealing. The process takes only a few minutes. Specifically, the successful surface preparation of doped SrTiO3 (001), LaAlO3 (001), NdGaO3 (001), DyScO3 (110), TbScO3 (110), MgO (001), and Al2O3 (0001) surfaces is demonstrated.