Gupta Siddharth, Joshi Pratik, Sachan Ritesh, Narayan Jagdish
Department of Materials Science and Engineering, Centennial Campus, North Carolina State University, Raleigh, NC 27695, USA.
Intel Corporation, Rolner Acres Campus 3, Hillsboro, OR 97124, USA.
Nanomaterials (Basel). 2022 Aug 8;12(15):2718. doi: 10.3390/nano12152718.
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.
为了在二维器件中利用石墨烯的快速传导特性，需要一种具有宽带隙且无陷阱的电介质的异质结构。在这种模式下，h-BN因其类似石墨烯的结构和超宽带隙而成为一个很好的候选材料。我们展示了如何通过用纳秒准分子激光辐照非晶碳（a-C）和非晶氮化硼（a-BN）薄膜的交替层，在此过程中熔化并进行区域精炼组成层，来制造这样的异质结构。通过拉曼光谱和飞行时间二次离子质谱（ToF-SIMS）分析，我们证明了这种局部区域精炼形成了具有不同拉曼振动模式的纯相h-BN和还原氧化石墨烯（rGO）薄膜，并且激光辐照后SIMS剖面图变平。此外，在比较激光辐照的rGO-Si金属-半导体（MS）二极管和rGO/h-BN/Si金属-绝缘体-半导体（MIS）二极管时，MIS二极管表现出开启电压增加（4.4 V）和低漏电流。MIS二极管的电流-电压（I-V）特性揭示了在低偏压下的直接隧穿传导以及在高电压区域的福勒-诺德海姆隧穿，从而使MIS二极管开启并具有改善的整流和电流流动特性。这项研究为开发用于超薄场效应晶体管器件的h-BN和石墨烯异质结构的非平衡方法提供了启示。
