| AVS 63rd International Symposium & Exhibition | |
| Advanced Surface Engineering | Wednesday Sessions |
| Session SE+2D+EM-WeA |
| Session: | Multifunctional Thin Films and Coatings |
| Presenter: | Adam Barton, The University of Texas at Dallas |
| Authors: | A.T. Barton, The University of Texas at Dallas R. Yue, The University of Texas at Dallas C.M. Smyth, The University of Texas at Dallas R. Addou, The University of Texas at Dallas L. Cheng, The University of Texas at Dallas R.M. Wallace, The University of Texas at Dallas J. Kim, The University of Texas at Dallas M. Kim, The University of Texas at Dallas J. Hsu, The University of Texas at Dallas K.J. Cho, The University of Texas at Dallas L. Colombo, Texas Instruments C.L. Hinkle, The University of Texas at Dallas |
| Correspondent: | Click to Email |
2D materials offer unique opportunities in device fabrication due to the weak van der Waals interaction between crystalline layers that allows for the growth of high-quality heterostructures with significantly less impact from lattice mismatch with the substrate. Hexagonal boron nitride (hBN) has a honeycomb structure similar to graphene except with alternating boron and nitrogen atoms. The hexagonal rings are composed of six sp2-hybridized atoms (three boron atoms and three nitrogen atoms). The electronic structure results in a bandgap of 5-7eV, a low-κ dielectric constant of 2-4εo, and an electron affinity of roughly 2 eV. These electronic properties make hBN an exciting material for a wide range of applications in electronic devices. In particular, we are interested in coupling hBN with transition metal dichalcogenides (TMDs) for low-power tunnel FET applications. Previous publications have primarily utilized chemical vapor deposition (CVD) to grow hBN on catalyzing transition metal substrates (Co, Ni, Cu, etc.) at growth temperatures ranging from 800-1200°C. However, these substrates and growth temperatures are not practical for the majority of device applications. Chalcogen loss in TMDs, for example occurs well below those temperatures.
In this work we report on our recent findings on the growth and characterization of hBN thin films grown by molecular beam epitaxy (MBE). This will include a detailed discussion of the growth mechanism on a variety of substrates (MoS2, HOPG, WSe2, Bi2Se3, and sapphire) using substrate growth temperatures ranging from 300-800°C. The impact of the source fluxes, substrate temperatures, and in particular, the presence of atomic hydrogen during growth will be presented. The hexagonal phase of BN is achieved as determined by diffraction, Raman, and XPS. AFM, TEM, and RHEED are also used to assess film quality and the experimentally determined bandgap and band alignment will be presented. We will also present our recent work on coupling hBN with ALD-deposited Al2O3 to enable higher-k gate dielectrics on top of 2D materials heterostructures.
This work is supported in part by the SWAN Center, a SRC center sponsored by the Nanoelectronics Research Initiative and NIST. This work was also supported in part by the Texas Higher Education Coordinating Board’s Norman Hackerman Advanced Research Program.