Integration of Two-dimensional Materials with Functional Dielectrics

• Applicant: Dr.-Ing. Alexander Henning, Ph.D.
• Subject Area: Microsystems ; Electrical Energy Systems, Power Management, Power Electronics, Electrical Machines and Drives ; Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; Synthesis and Properties of Functional Materials ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2017 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 386647094

• Final Report Year: 2019

Final Report Abstract

The integration of two-dimensional van der Waals materials with dielectrics is a key challenge that needs to be addressed to make these materials a viable platform for technology. The goal of the proposed research was to enable device functionality by integration of two-dimensional materials with dielectrics in such a way that the intrinsic properties of the 2D semiconductor are largely preserved. The applicant implemented low-temperature thermal atomic layer deposition for the integration of two-dimensional van der Waals materials with dielectrics. Nucleation of dielectrics on vdW materials was facilitated with a highly reactive metalorganic precursor (ALD MoOx on MoS2) or with an organic seeding layer (ALD Al2O3 on InSe). It was demonstrated that ALD-grown adlayers protect the 2D semiconductor from ambient degradation, improve the field-effect mobility and allow controlling the charge carrier concentration in 2D MoS2 field-effect transistors via charge transfer. Furthermore, it was found that ALD-grown MoOx is mainly held by vdW interactions on the 2D materials, thus it encapsulates the 2D semiconductor while largely preserving its optoelectronic properties. These findings are vital for the application and design of novel 2D p-n homojunctions and FETs. This research was accomplished in a close collaboration between the Departments of Materials Science & Engineering and Chemistry at Northwestern University.

Publications

• (2018): Atomic Layer Deposition of Molybdenum Oxides with Tunable Stoichiometry Enables Controllable Doping of MoS2, Chem. Mater., 30,11, 3628-3632
  Henning, A., Moody, M.J., Jurca, T., Shang J., Bergeron, H., Balla, I., Olding, J.N., Weiss, E.A., Hersam, M.C., Lohr, T.L., Marks, T.J., Lauhon, L.J.
  
• (2018): Charge separation at a mixed-dimensional single and multilayer MoS2/silicon nanowire heterojunctions, ACS Appl. Mater. Interfaces., 10,19, 16760-16767
  Henning, A., Sangwan, V.K., Bergeron, H., Balla, I., Sun, Z., Hersam, M.C., Lauhon, L.J.
  
• (2018): Stoichiometry of Atomic-Layer-Deposition-Grown MoOx Controls Carrier Concentration in Monolayer MoS2. Conference: Material Research Society (MRS) spring meeting, Phoenix (USA), 04/05/2018
  Henning, A., Moody M.J., Shang J., Bergeron, H., Balla, I., Jurca, T., Marks, T.J., Hersam, M.C., Lauhon, L.J.
  
• (2018): Suppressing Ambient Degradation of Exfoliated InSe Nanosheet Devices via Seeded Atomic Layer Deposition Encapsulation, Nano Lett.,18,12, 7876-7882
  Wells, S.A., Henning, A., Gist, J.T., Sangwan, V.K., Lauhon, L.J., Hersam, M.C.