Journal
NANOMATERIALS
Volume 12, Issue 15, Pages -Publisher
MDPI
DOI: 10.3390/nano12152718
Keywords
Raman spectroscopy; h-BN; 2D materials; laser irradiation; graphene; molecular dynamics; Fowler-Nordheim tunneling; transmission electron microscopy
Categories
Funding
- NSF [DMR-2016256]
- ARO [W911NF-17-1-0596]
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This study demonstrates the fabrication of heterostructures with graphene and h-BN using laser irradiation. The results show that phase-pure h-BN and reduced graphene oxide films can be obtained through localized zone-refining. The newly fabricated diodes exhibit improved rectification and current flow characteristics compared to previous diodes, with increased turn-on voltage and low leakage current.
To employ graphene's rapid conduction in 2D devices, a heterostructure with a broad bandgap dielectric that is free of traps is required. Within this paradigm, h-BN is a good candidate because of its graphene-like structure and ultrawide bandgap. We show how to make such a heterostructure by irradiating alternating layers of a-C and a-BN film with a nanosecond excimer laser, melting and zone-refining constituent layers in the process. With Raman spectroscopy and ToF-SIMS analyses, we demonstrate this localized zone-refining into phase-pure h-BN and rGO films with distinct Raman vibrational modes and SIMS profile flattening after laser irradiation. Furthermore, in comparing laser-irradiated rGO-Si MS and rGO/h-BN/Si MIS diodes, the MIS diodes exhibit an increased turn-on voltage (4.4 V) and low leakage current. The MIS diode I-V characteristics reveal direct tunneling conduction under low bias and Fowler-Nordheim tunneling in the high-voltage regime, turning the MIS diode ON with improved rectification and current flow. This study sheds light on the nonequilibrium approaches to engineering h-BN and graphene heterostructures for ultrathin field effect transistor device development.
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