Film deposition by thermal laser evaporation

We study the thermal evaporation of materials by irradiation with laser light to deposit layers with atomically precise thickness. Under ultrahigh to moderate vacuum pressures, a focused laser beam is directed to the front surface of a source target to heat it to temperatures suitable for thermal evaporation. The local heating, combined with efficient radiative heat dissipation at high temperatures, allows the evaporation of solid elements from self-supported targets, eliminating the need for crucibles. The temperature is controlled by a sensor on the back of the target with feedback to the laser power. Evaporating representative metals, we achieve ultrahigh evaporation temperatures exceeding 2000 °C as well as temperature stabilities of better than ±0.1 °C. Combined with laser substrate heating, this enables a thermal laser epitaxy process that is capable in principle of accurately co-depositing any combination of chemical elements at any substrate temperature under a vacuum pressure only to provide a mean free path exceeding the target–sample distance.