Superconductor-to-insulator transition in boron-doped diamond films grown using chemical vapor deposition

Akihiro Kawano, Hitoshi Ishiwata, Shingo Iriyama, Ryosuke Okada, Takahide Yamaguchi, Yoshihiko Takano, and Hiroshi Kawarada

Phys. Rev. B 82, 085318 – Published 16 August 2010

Abstract

The critical concentration of superconductor-to-insulator transition in boron-doped diamond is determined in two ways, namely, the actual doping concentration of boron and the Hall carrier concentration. Hall carrier concentrations in (111) and (001) films exceed the actual doping concentration owing to the distortion of the Fermi surface. The high critical boron concentration in (110) films is owing to the effect of the high concentration of interstitial boron atoms. A boron concentration of $3 \times 10^{20} {cm}^{- 3}$ in substitutional site is required for inducing superconductivity in diamond.

Received 29 May 2010

DOI:https://doi.org/10.1103/PhysRevB.82.085318

Authors & Affiliations

Akihiro Kawano¹, Hitoshi Ishiwata¹, Shingo Iriyama¹, Ryosuke Okada¹, Takahide Yamaguchi², Yoshihiko Takano², and Hiroshi Kawarada¹

¹School of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan
²National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Japan

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Issue

Vol. 82, Iss. 8 — 15 August 2010

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Images

Figure 1
(Color online) Dependence of $T_{C}$ on boron concentration measured by SIMS. Triangle plots are for (111) boron-doped diamond films, square plots for (001) films, and diamond-shaped plots for (110) films. Solid lines are drawn so as to fit the data in the plots. The dashed line shows the measurement limit of the temperature (0.4 K) in our ${}^{3}H e$ cooling system. The critical boron concentrations of superconductor-to-insulator transition are estimated to be $3 \times 10^{20} {cm}^{- 3}$ in (111) and (001) films and $9 \times 10^{20} {cm}^{- 3}$ in (110) films.Reuse & Permissions
Figure 2
(Color online) Dependence of $T_{C}$ on carrier concentration estimated by Hall effect measurement. Triangle plots are for (111) boron-doped diamond films, square plots for (001) films, and diamond-shaped plots for (110) films. Solid lines are drawn so as to fit the data in plots. All of the solid lines approach $4 \times 10^{20} {cm}^{- 3}$ at zero temperature. The critical carrier concentrations of superconductor-to-insulator transition are estimated to be $4 \times 10^{20} {cm}^{- 3}$ .Reuse & Permissions
Figure 3
(Color online) Relationship between carrier concentration $n_{H}$ and boron concentration $n_{B}$ in (111) films. The dotted line is a fit to $n_{H} / n_{B} = 1$ (one carrier per boron atom). The dashed line shows the critical boron concentration of superconductor-to-insulator transition in (111) and (001) films $(= 3 \times 10^{20} {cm}^{- 3})$ . The carrier concentration exceeds the boron concentration for $n_{B} ≳ 3 \times 10^{20} {cm}^{- 3}$ . In contrast, the carrier concentration is the below boron concentration for $n_{B} ≲ 3 \times 10^{20} {cm}^{- 3}$ . Inset is a schematic of the Fermi surface in the (111) plane of $k$ space. The Fermi surface extends along the {110} directions.Reuse & Permissions
Figure 4
(Color online) Perpendicular lattice expansion as a function of boron concentration: triangle plots are for (111) boron-doped diamond films, square plots for (001) films, and diamond-shaped plots for (110) films. Open square plots are reported by Bustarret et al. Dashed line shows the Vegard’s law using the covalent bonding radii $r_{B}$ and $r_{C}$ of 0.088 nm and 0.077 nm, respectively. Dotted line is drawn so as to fit the data in plots of (110) films.Reuse & Permissions
Figure 5
(Color online) Dependence of $T_{C}$ on (a) perpendicular and (b) in-plane lattice expansion ratio deduced by x-ray diffraction. Triangle plots are for (111) boron-doped diamond films, square plots for (001) films, and diamond-shaped plots for (110) films. Solid lines are drawn so as to fit the data in plots. Insets are the shape of the lattice expansion of (111) and (001) samples.Reuse & Permissions

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