Ultra-doped semiconductors by non-equilibrium processing for electronic, photonic and spintronic applications

Doping is the key to making semiconductors functional. Ultra-doping or Hyperdoping refers to introducing dopant concentrations far above the solid solubility limits. This leads to the broadening of dopant energy level into a separated or merged impurity band with interesting consequences in terms of (opto)electronic, magnetic or superconducting properties.

Scope:

In 1931, Wolfgang Pauli said “One shouldn’t work on semiconductors, that is a filthy mess; who knows whether any semiconductors exist”. We know it is doping that makes semiconductor exist and functional. Doping is the intentional introduction of impurities into an intrinsic semiconductor for the purpose of modulating its electrical, optical and structural properties. It is the indispensable step in the integrated-circuit industry production line. The ultra-doping or hyperdoping of semiconductors refers to introducing dopant concentrations far above the solid solubility limits. This leads to the broadening of dopant energy level into a separated or merged impurity band with interesting consequences in terms of optoelectronic, magnetic or superconducting properties. Here, the dopants also include those elements, that are far away from the host semiconductor in the element table and have large ionization energies. By hyperdoping, semiconductors can be turned to metals, superconductors (such as boron doped diamond/Si/Ge), or ferromagnets (such as Mn doped III-V compounds). The applications spread from electronics, spintronics, quantum technology to optoelectronics, with the first practical devices appearing recently. To overcome the solid solubility limit, methods far away from thermal equilibrium, such as ion implantation and low-temperature molecular beam epitaxy, are used. Minimized post-doping thermal process is also necessary to reduce the diffusion. Even so, it is still a question if the introduced dopants are randomly distributed in the substitutional lattice positions. Therefore, proper atomic-scale characterization is also needed to verify the dopant distribution and chemical states. This symposium will be highly interdisciplinary, attracting participants from semiconductor, nanoelectronics, optoelectronics, plasmonics, superconductor and magnetism communities.

Hot topics to be considered:

• Optoelectronic devices based on hyperdoped Si, Ge, III-V and GeSn including photodetectors at infrared wavelength
• Hyperdoped semiconductors (Si, Ge and III-V) for plasmonics: tunable plasmonic frequency by doping concentration, plasmonic structural design
• Hyperdoped semiconductors (Si, Ge, SiGe and GeSn) for future field-effect transistors
• Highly mismatched alloys, such as GeSn, SiGeSn, GaAsN, GaPN …
• Ferromagnetic semiconductors, including transition metal doped III-V and IV semiconductors and their structural characterization
• Diamond, Si, Ge and SiC based superconductors: Boron doping, superconducting properties, application for quantum technology
• Manufacturing hyperdoped and mismatched materials – Out of the equilibrium techniques, including ion implantation, low-temperature molecular beam epitaxy, low-temperature chemical vapor deposition, pulsed laser melting and flash lamp annealing
• Advanced characterization technologies for impurities and defects at atomic scale: including Atom probe tomography (APT), High resolution transmission electron microscopy, Rutherford backscattering/channeling, Emission channeling, X-ray spectroscopies
• First-principle calculation regarding the impurity and defect configuration
• Challenges for doping emerging materials, such as 2D semiconductors, ultra-wide bandgap semiconductors and topological insulators
• New concepts for doping, such as polarization-induced hole doping in wide-bandgap semiconductors

List of invited speakers:

• Jean-Michel Hartmann (Leti-CEA, France): Epitaxy of heavily in-situ doped group-IV semiconductors
• Antonino La Magna (CNR-IMM, Catania): Simulation challenges for hyperdoping by Pulsed Laser Melting
• Jacopo Frigerio (LNESS-Politecnico di Milano): Ge hyperdoping for advanced photonic devices
• Hung (henry) Hsiang Cheng (National Taiwan University): Hybrid semiconductor photodetector
• Ray Duffy (Tyndall National Institute, Ireland): Doping challenges for future nanoelectronic devices
• Qiang Wu (Nankai University, China): Hyperdoped Silicon Photodetectors Fabricated by Femtosecond Laser
• Francesca Chiodi (Université Paris-Saclay, France): Nanosecond laser doped silicon: effect of doping and strain on superconductivity
• Daniel Hiller (TU-Freiberg, Germany): Conventional Impurity Doping vs. Modulation Doping of Silicon Nanostructures
• Moritz Hoesch (Desy, Germany): Active Sites of Te-hyperdoped Silicon by Hard X-ray Photoelectron Spectroscopy
• Jan Siegel (CSIC, Spain): Femtosecond laser processing of semiconductors: Strategies, structures and underlying mechanisms