Laser Molecular Beam Epitaxy (Laser-MBE)

Laser-MBE (also known as pulsed laser deposition, PLD) is used for growing thin films from stoichiometric targets out of thermal equilibrium. A pulsed ultraviolet laser beam produces a stoichiometric plasma plume out of the polycrystalline target material. The substrate sits within this plasma plume so that a thin film of the plasma material is being deposited onto the substrate. Because of their high melting points, PLD is especially suited for growing thin oxide films.

In our system, the substrate is heated from the back by an infrared heating laser at a wavelength of 938 nm with a maximum power of 140 W located outside the deposition chamber. The temperature is also measured from outside the chamber using a two-color pyrometer. On silicon substrates, we achieve a maximum temperature of 1300°C. At the bottom there are five polycrystalline PLD targets mounted on a target carousel. An ultraviolet laser beam from a KrF excimer laser (Lambda Physik COMPex 201) of 248 nm with a pulse energy of 680 mJ and a repetition rate of 10 Hz is focused by a telescope objective onto the target surface. An in-situ RHEED system is used to monitor the growth process.

Advantages:

• stoichiometric transfer of material
• high deposition rates
• high flexibility and variety of materials

Our PLD system is used for growing magnetic, ferroelectric, semiconducting, and insulating oxides, like Sr₂CrReO₆, BiCrO₃, BaTiO₃, SrTiO₃, Fe₃O₄, Y₃Fe₅O₁₂, NiO, and ZnO.