title: Deionization of Dopants in Silicon Nanofilms Even with Donor Concentration of Greater than 10(19) cm(-3).
abstract: Understanding the dopant properties in heavily doped nanoscale semiconductors is essential to design nanoscale devices. We report the deionization or finite ionization energy of dopants in silicon (Si) nanofilms with dopant concentration (ND) of greater than 10(19) cm(-3), which is in contrast to the zero ionization energy (ED) in bulk Si at the same ND. From the comparison of experimentally observed and theoretically calculated ED, we attribute the deionization to the suppression of metal-insulator transition in highly doped nanoscale semiconductors in addition to the quantum confinement and the dielectric mismatch, which greatly increase ED in low-doped nanoscale semiconductors. Thus, for nanoscale transistors, ND should be higher than that estimated from bulk Si dopant properties in order to reduce their resistivity by the metal-insulator transition.
authors.affiliation: Department of Electronics and Electrical Engineering, Faculty of Science and Technology, Keio University , Hiyoshi, Yokohama 223-8522, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Department of Physical Electronics and Quantum Nanoelectronics Research Center, Tokyo Institute of Technology , Meguro, Tokyo 152-8552, Japan.
authors.forename: Yuya
authors.initials: Y
authors.lastname: Kurosawa
authors.affiliation: Department of Physical Electronics and Quantum Nanoelectronics Research Center, Tokyo Institute of Technology , Meguro, Tokyo 152-8552, Japan.
authors.forename: Naotoshi
authors.initials: N
authors.lastname: Kadotani
authors.affiliation: Department of Electronics and Electrical Engineering, Faculty of Science and Technology, Keio University , Hiyoshi, Yokohama 223-8522, Japan.
authors.forename: Tsunaki
authors.initials: T
authors.lastname: Takahashi
authors.affiliation: Department of Physical Electronics and Quantum Nanoelectronics Research Center, Tokyo Institute of Technology , Meguro, Tokyo 152-8552, Japan.
authors.forename: Shunri
authors.initials: S
authors.lastname: Oda
authors.affiliation: Department of Electronics and Electrical Engineering, Faculty of Science and Technology, Keio University , Hiyoshi, Yokohama 223-8522, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Uchida
keywords: Ionization energy; metal−insulator transition; nanostructure; phosphorus; silicon; transistor