title: Exploring the limits of N-type ultra-shallow junction formation.
abstract: Low resistivity, near-surface doping in silicon represents a formidable challenge for both the microelectronics industry and future quantum electronic devices. Here we employ an ultra-high vacuum strategy to create highly abrupt doping profiles in silicon, which we characterize in situ using a four point probe scanning tunnelling microscope. Using a small molecule gaseous dopant source (PH3) which densely packs on a reconstructed silicon surface, followed by encapsulation in epitaxial silicon, we form highly conductive dopant sheets with subnanometer control of the depth profiles. This approach allows us to test the limits of ultra-shallow junction formation, with room temperature resistivities of 780 Ω/□ at an encapsulation depth of 4.3 nm, increasing to 23 kΩ/□ at an encapsulation depth of only 0.5 nm. We show that this depth-dependent resistivity can be accounted for by a combination of dopant segregation and surface scattering.
authors.affiliation: School of Physics, University of New South Wales, Sydney, New South Wales 2052, Australia. craig.polley@maxlab.lu.se
authors.forename: Craig M
authors.initials: CM
authors.lastname: Polley
authors.forename: Warrick R
authors.initials: WR
authors.lastname: Clarke
authors.forename: Jill A
authors.initials: JA
authors.lastname: Miwa
authors.forename: Giordano
authors.initials: G
authors.lastname: Scappucci
authors.forename: Justin W
authors.initials: JW
authors.lastname: Wells
authors.forename: David L
authors.initials: DL
authors.lastname: Jaeger
authors.forename: Maia R
authors.initials: MR
authors.lastname: Bischof
authors.forename: Richard F
authors.initials: RF
authors.lastname: Reidy
authors.forename: Brian P
authors.initials: BP
authors.lastname: Gorman
authors.forename: Michelle
authors.initials: M
authors.lastname: Simmons