Thermal laser evaporation of elements from across the periodic table

March 22, 2021

Thin-film devices are becoming increasingly common in our everyday lives, with applications varying from touch screens to rechargeable batteries to thin solar cells.  As further potential applications emerge, the demand for synthesizing highly pure thin-film compounds composed of vastly different constituents from across the periodic table is growing accordingly. At the same time, high-power lasers have become affordable and sufficiently practical in the past decade, meaning that vapors of many individual elemental sources can be generated for film growth. This has paved the way for thermal laser evaporation (TLE), a new method to grow thin films that utilizes continuous-wave laser heating and evaporation of individual freestanding elemental sources, see Fig. 1.

Fig. 1: Simplified artistic representation of TLE. A CW heating laser is incident upon a freestanding elemental source, heating it to temperatures where significant evaporation of the source occurs. This elemental vapor is then deposited onto a substrate heated by a laser.

Recently, as published in Journal of Laser Application 33, 022008 (2021) – Open Access, our team at the Max Planck Institute for Solid State Research has demonstrated the immense promise of TLE by showing that it can not only evaporate more than 40 elements from across the periodic table, it can also grow thin films for each element. By testing elements with different extreme growth parameters (including melting point, thermal conductivity and others), we found that TLE can be applied to any solid, non-radioactive element in the periodic table, allowing any feasible compound to be grown using elements having significantly different physical properties. For all the elements we tested, significant growth rates were achieved using less than 500 W of output laser power, resulting in a total power requirement comparable to other film growth techniques.

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