PNNL

Molecular beam epitaxy (MBE) and pulsed laser deposition (PLD) are physical vapor transport methods used to fabricate single crystal thin films and multilayers to discover new physical properties to enable future technological advances. These techniques produce exceptionally high-quality thin films with atomic-level control of the crystal film’s orientation, phase, and stoichiometry in a nearly contamination-free ultrahigh-vacuum environment. At the Energy Sciences Center (ESC), MBE and PLD are used to advance the frontiers of chemistry and materials science research through the creation of high-quality complex oxide thin films for next-generation microelectronics, spintronics, quantum computing, catalysis, and energy storage applications.

The ESC’s two MBE deposition systems are a flexible platform for the deposition of a wide variety of single crystal thin films, and both offer powerful in situ characterization capabilities. Each MBE is equipped with several high-purity metal sources (transition metals, alkaline earth metals, and lanthanides) in individual effusion cells, electron beam evaporators for high-temperature refractory metals, and a plasma unit to generate highly reactive oxygen species. Film deposition is monitored in real time using reflection high-energy electron diffraction (RHEED). Both systems offer in situ high-resolution X-ray photoelectron spectroscopy in appended ultrahigh-vacuum chambers for physical and electronic structure characterization without exposing the film to atmospheric contaminants. The ESC’s PLD system consists of two separate deposition chambers to maximize the selection of oxide and nitride source materials. Source material ablation occurs using a 248 nm pulsed excimer laser, and computer control allows ablation of multiple source targets in sequence to facilitate the deposition of doped films, multilayers, and combinatorial films with compositional gradients. In situ high-pressure RHEED can be used to monitor thin film deposition in real time.

Research Application

• Design and discovery of new materials through controlled synthesis and processing.
• Engineering the electronic, optical, and magnetic properties of complex oxide heterostructures to enable their applications in microelectronics, spintronics, and quantum information science.
• Using isotope-labeled single crystal oxides to quantify the atomic diffusion and transport phenomena occurring in critical materials used in thermal barrier coatings, solid oxide fuel cells, and nuclear reactors.
• Understanding charge and mass transfer mechanisms in structurally ordered materials for the predictive synthesis of next-generation catalysts, electrocatalysts, and energy storage materials and devices.
• Utilizing epitaxial films as synthetic model minerals to enhance understanding of geochemical and biogeochemical controls on environmental contaminant fate and transport.