Contact resistance of various metallisation schemes to superconducting boron doped diamond between 1.9 and 300 K

TL;DR

This study evaluates the stability and resistance of various metallisation schemes to superconducting boron-doped diamond across a temperature range from 1.9 to 300 K, highlighting temperature-dependent contact resistances.

Contribution

It provides a comparative analysis of different contact schemes' stability and resistance at cryogenic temperatures on boron-doped diamond, extending previous room-temperature studies.

Findings

All contact schemes remained ohmic down to cryogenic temperatures.

Significant temperature dependence of contact resistance was observed at Tc.

Ta/Pt/Au contact exhibited the lowest resistance at cryogenic temperatures.

Abstract

Diamond is a material that offers potential in numerous device applications. In particular, highly boron doped diamond is attractive due to its superconductivity and high Young's Modulus. The fabrication of stable, low resistance, ohmic contacts is essential to ensure proper device function. Previous work has established the efficacy of several methods of forming suitable contacts to diamond at room temperature and above, including carbide forming and carbon soluble metallisation schemes. Herein, the stability of several contact schemes (Ti, Cr, Mo, Ta and Pd) to highly boron doped nanocrystalline diamond was verified down to the cryogenic temperatures with modified Transmission Line Model (TLM) measurements. While all contact schemes remained ohmic, a significant temperature dependency is noted at Tc and at the lowest temperatures the contact resistances ranged from Ti/Pt/Au with ${(8.83 \pm 0.10)\times 10^{-4} \:{\Omega}.cm}$ to Ta/Pt/Au with ${(8.07 \pm 0.62) \times 10^{-6} \:{\Omega}.cm}$.