Atomistic Understanding of a Single Gated Dopant Atom in a MOSFET
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1067-B03-07
Atomistic Understanding of a Single Gated Dopant Atom in a MOSFET Gabriel Lansbergen1, Rajib Rahman2, Cameron Wellard3, Jaap Caro1, Nadine Collaert4, Serge Biesemans4, Gerhard Klimeck2,5, Lloyd Hollenberg3, and Sven Rogge1 1 Kavli institute of nanoscience, TU Delft, Delft, 2628 CJ, Netherlands 2 Network for Computational Nanotechnology, Purdue University, West Lafayette, IN, 47907 3 Center for Quantum Computer Technology, University of Melbourne, Melbourne, VIC 3010, Australia 4 IMEC, Leuven, 3001, Belgium 5 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109 ABSTRACT Current semiconductor devices have been scaled to such dimensions that we need take an atomistic approach to understand their characteristics. The atomistic nature of these devices provides us with a tool to study the physics of very small ensembles of dopants right up to the limit of a single atom. Control and understanding of a dopants wavefunction and its coupling to the environment in a nanostructure could proof a key ingredient for device technology beyondCMOS. Here, we will discuss the eigenlevels and transport characteristics a single gated As donor. These donors are incorporated in the channel of a wrap-around gate transistors (FinFET). The measured level spectrum is shown to consist of levels associated with the donors Coulomb potential, levels associated with a triangular well at the gate interface and hybridized combinations of the two. The level spectrum of this system can be well described by a NEMO3D model, which is based on a numerical tight-binding approximation. INTRODUCTION Isolated donors in silicon have received renewed attention in the last decade due to their potential use for quantum electronics [1-4]. An isolated donor forms a 3D Coulomb (thus truly atomistic) potential in the silicon lattice and can bind up to two electrons [5]. The isolated donors typically act as the binding sites for electrons with the information carried by either the electronspin or -charge. The ability to perform operations with such structures is crucially provided by one (or more) gate electrodes around the donor site. Although much interest exists in the functionality that can be derived from isolated donors, experimental access to only a single donor has proven to be difficult [6-8]. Here, we will discuss resonant tunneling spectroscopy measurements on the eigenlevels of single As donors in a three terminal configuration, i.e. a gated donor which is a basic element for quantum electronics. These donors are incorporated in the channel of (p-type) prototype transistors called FinFETs. The local electric field due to the built-in voltage between the channel and the gate electrode forms a triangular potential at the interface. We will show that by means of spectroscopic measurements we can identify states to be associated with either the donors Coulomb potential, the triangular well or a hybridized combinations of the two. The theoretical framework used to describe this system is based on a tight binding approxi
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