Thermal laser epitaxy

[1] [2] This technique can be performed under ultra-high vacuum pressure or in the presence of a background atmosphere, such as ozone, to deposit oxide films.

[3] TLE operates at power densities between 104 – 106 W/cm2, which results in evaporation or sublimation of the source material, with no plasma or high-energy particle species being produced.

[4] TLE uses continuous-wave lasers (typically with a wavelength of around 1000 nm) located outside the vacuum chamber to heat sources of material in order to generate a flux of vapor via evaporation or sublimation.

Heat loss via conduction and radiation further localizes the high-temperature region close to the irradiated surface of the source.

[5][6] By positioning all lasers outside of the evaporation chamber, contamination can be reduced compared to using in situ heaters, resulting in highly pure deposited films.

The deposition rate of the vapor impinging upon the substrate is controlled by adjusting the power of the incident source laser.

Diagram of a TLE chamber. Continuous-wave lasers are focused on sources inside a vacuum chamber. The localized heating induced by these lasers creates a flux of vapor from each source, which is then deposited onto a heated substrate. A gaseous atmosphere can be introduced via a gas inlet to grow compounds such as oxides. [ 1 ]
Photograph of a freestanding silicon disc being heated locally by a laser in a TLE chamber. [ 4 ]