| AVS 61st International Symposium & Exhibition | |
| 2D Materials Focus Topic | Monday Sessions |
| Session 2D+EM+NS+PS+SS+TF-MoM |
| Session: | 2D Materials Growth and Processing |
| Presenter: | Andrey Voevodin, Air Force Research Laboratory |
| Authors: | A.A. Voevodin, Air Force Research Laboratory C. Muratore, University of Dayton J.J. Hu, Air Force Research Laboratory/UDRI B. Wang, Pennsylvania State University M.A. Haque, Pennsylvania State University J.E. Bultman, Air Force Research Laboratory/UDRI M.L. Jesperson, Air Force Research Laboratory/UDRI P.J. Shamberger, Texas A&M University R. Stevenson, Air Force Research Laboratory A. Waite, Air Force Research Laboratory/UTC M.E. McConney, Air Force Research Laboratory R. Smith, Air Force Research Laboratory |
| Correspondent: | Click to Email |
Growth of two dimensional (2D) MoS2 and similar materials over large areas is a critical pre-requisite for seamless integration of next-generation van der Waals heterostructures into novel devices. Typical preparation approaches with chemical or mechanical exfoliation lack scalability and uniformity over appreciable areas (>1 mm) and chemical vapor deposition processes require high substrate temperatures. We developed few-layer MoS2 growth under non-equilibrium magnetron sputtering conditions selected to minimize the MoS2 nucleation density and maximize 2D growth of individual crystals [1]. In this process, the thermodynamically driven tendency to form islands is accomplished by maximizing atomic mobility through the control of incident flux kinetic energies, densities, and arriving angle to the substrate while avoiding defect formation (i.e., vacancy creation by sputtering of S atoms). Amorphous SiO2, crystalline (0001) oriented Al2O3, and (002) oriented graphite substrates were used to grow few monolayer thick MoS2 films. Continuous 2D MoS2 films were produced over 4 cm2 areas. They were composed of nano-scale domains with strong chemical binding between domain boundaries, allowing lift-off from the substrate and electronic transport measurements with contact separation on the order of centimeters. Their characteristics were similar to few-layer MoS2 films produced by exfoliation with a direct band gap in thin samples of approximately 1.9 eV from photoluminescense spectra. The electron mobility measured for as-grown MoS2 films was very strongly dependent on film thickness and substrate choice.
[1] “Continuous ultra-thin MoS2 films grown by low-temperature physical vapor deposition”, C. Muratore, J.J. Hu, B. Wang, M.A. Haque, J.E. Bultman, M. L. Jesperson, P.J. Shamberger, A.A. Voevodin, Applied Physics Letters (2014) in press.