Growth Optimization of Epitaxial Transition Metal Dichalcogenides

3D materials such as silicon have been the workhorse of the semiconductor industry for decades. However, as transistor technology approaches nanoscale, the performance of these materials is seriously impacted by short-channel effects. Monolayer Transition Metal Dichalcogenides (TMDs) have been shown to exhibit modest and direct bandgaps, making them ideal candidates for next-gen semiconductors. Exfoliated materials are typically of high quality but aren't scalable. Molecular Beam Epitaxy (MBE) can deposit large-area films with atomically precise thickness, as well as precisely composition control, making it an ideal method for studying the transport properties of TMDs. While the growth of TMDs on c-sapphire is common in chemical vapor deposition (CVD), it's use in MBE growth is uncommon due to the large lattice mismatch between TMDs and c-sapphire. Growth on c-sapphire by MBE requires temperatures 900°C and higher in an UHV atmosphere to make oriented films, without which, a randomly oriented polycrystalline film is obtained. Our films are grown with precise thickness and are highly crystalline and uniform. We'll discuss growth optimization and characterization of these films.