Low-temperature transport in highly boron-doped nanocrystalline diamond

Philipp Achatz (1) , Wojciech Gajewski (2) , Etienne Bustarret (1) , C. Marcenat (3) , Raoul Piquerel (4) , Claude Chapelier (3) , Thomas Dubouchet (3) , O. A. Williams (5) , Ken Haenen (6) , Jose Antonio Garrido (2) , Martin Stutzmann (2)

1 NEEL - SC2G - Semi-conducteurs à large bande interdite
2 WSI - Walter Schottky Institut
3 LaTEQS - Laboratoire de Transport Electronique Quantique et Supraconductivité
4 NEEL - QuantECA - Circuits électroniques quantiques Alpes
5 Fraunhofer IAF - Fraunhofer Institute for Applied Solid State Physics
6 Institute for Materials Research

We studied the transport properties of highly boron-doped nanocrystalline diamond thin films at temperatures down to 50 mK. The system undergoes a doping-induced metal-insulator transition with an interplay between intergranular conductance g and intragranular conductance g0, as expected for a granular system. The conduction mechanism in the case of the low-conductivity films close to the metal-insulator transition has a temperature dependence similar to Efros-Shklovskii type of hopping. On the metallic side of the transition, in the normal state, a logarithmic temperature dependence of the conductivity is observed, as expected for a metallic granular system. Metallic samples far away from the transition show similarities to heavily borondoped single-crystal diamond. Close to the transition, the behavior is richer. Global phase coherence leads in both cases to superconductivity also checked by ac susceptibility , but a peak in the low-temperature magnetoresistance measurements occurs for samples close to the transition. Corrections to the conductance according to superconducting fluctuations account for this negative magnetoresistance.

Domaines: Supraconductivité [cond-mat.supr-con]; Systèmes désordonnés et réseaux de neurones [cond-mat.dis-nn]

Philipp Achatz, Wojciech Gajewski, Etienne Bustarret, C. Marcenat, Raoul Piquerel, et al.. Low-temperature transport in highly boron-doped nanocrystalline diamond. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2009, 79 (20), pp.201203(R). ⟨10.1103/PhysRevB.79.201203⟩. ⟨hal-00760974⟩