SGM 15

Ohmic contact engineering in few-layer black phosphorus: approaching the quantum limit

Achieving a good quality Ohmic contact on van der Waals materials is a challenge, since at the interface between metal and van der Waals material, different interface conditions could apply, ranging from the presence of a large energy barrier to the metallization of the layered material below the contacts. In black phosphorus (bP) a further challenge is its high reactivity to oxygen and moisture, which makes comparison among different experiments difficult, since the presence of uncontrolled oxidation can substantially change the behavior of the contacts. In this study, we tested the influence of the metal used for the contacts against flakes and sample variability, using three of the most used metals as contacts: chromium, titanium, and nickel. From an analysis of nine different devices, using the transfer length method at both room and at low temperature, Ni appears to be the best candidate for Ohmic contacts to bP, providing the lowest contact resistance and a very low scattering between different devices, see Fig. 1. Moreover, we investigate the gate dependence of the current–voltage characteristics of field–effect transistors fabricated with these metals on bP, observing good linearity in the accumulation regime for all metals investigated.


Figure 1: Transfer length method: average two-probe resistance R2 at low temperature as a function of contact distance d. The solid lines are the results of a linear fit procedure. Outside the range of fitting, the same linear function is plotted using dashed lines.

Publications:

  1. Gwenael le Gal: Ohmic contact engineering and low temperature magneto-transport measurements in few-layer Black Phosphorus, Internship Report, May – July 2017.
  2. Francesca Telesio, Gwenael le Gal, Manuel Serrano-Ruiz, Federico Prescimone, Stefano Toffanin, Maurizio Peruzzini, and Stefan Heun: Ohmic contact engineering in few-layer black Phosphorus field effect transistors, arXiv:1905.05649 [cond-mat.mes-hall].
  3. F. Telesio, G. Le Gal, M. Serrano-Ruiz, F. Prescimone, S. Toffanin, M. Peruzzini, and S. Heun: Ohmic contact engineering in few-layer black phosphorus: approaching the quantum limit, Nanotechnology 31 (2020) 334002.

Presented at:

  1. Gwenael le Gal: Ohmic contact engineering in few layer Black Phosphorus, Internship Final Presentation, July 2017.
  2. Francesca Telesio, Gwenael le Gal, Manuel Serrano-Ruiz, Federico Prescimone, Stefano Toffanin, Maurizio Peruzzini and Stefan Heun: Ohmic contact engineering in few-layer black phosphorus field effect transistors, E-MRS Spring Meeting 2019, Nice, France, 27 – 31 May 2019 (oral). [Abstract] [Talk]
  3. F. Telesio, G. le Gal, M. Serrano-Ruiz, F. Prescimone, S. Toffanin, M. Peruzzini, and S. Heun: Ohmic contact engineering in few-layer black Phosphorus field effect transistors, FisMat 2019, Catania, Italy, 30 September – 4 October 2019 (oral). [Abstract] [Talk]