(Invited) Scalable Planar Fabrication Processes for Chalcogenide-Based Topological Insulators

Abstract

The long spin diffusion lengths predicted for surface transport in topological insulators could lead to numerous applications. Many of the physics experiments used to show promising transport properties were conducted on exfoliated flakes from bulk material, thin films on substrates of limited dimensions, or bulk material, with limited yield. A planar thin film-based technology is needed to make topological insulator devices at a large scale, which is advantageous for applications and could also lead to new device designs. We address two problems related to fabricating chalcogenide-based topological insulator devices on large 3” wafers in the modern microfabrication facility at Sandia National Laboratories using polycrystalline and epitaxial Bi2Te3 films as a prototypical example. (1) Selective inhomogeneous doping was accomplished using ion implantation. Implantation damage and its subsequent mitigation through annealing is characterized. (2) Dielectric layers are often used to manipulate surface potential for elucidating topological surface state transport. We found that the quality of the gate dielectric can show significant degradation with different processing conditions. The leakage current is characterized as a function of temperature. Solutions to these problems are explored and discussed. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract No. DE-AC04-94AL85000.