Abstract
Semiconductors have long been perceived as a prerequisite for solid-state transistors. Although switching principles for nanometer-scale devices have emerged based on the deployment of two-dimensional (2D) van der Waals heterostructures, tunneling and ballistic currents through short channels are difficult to control, and semiconducting channel materials remain indispensable for practical switching. In this study, we report a semiconductor-less solid-state electronic device that exhibits an industry-applicable switching of the ballistic current. This device modulates the field emission barrier height across the graphene-hexagonal boron nitride interface with ION/IOFF of 106 obtained from the transfer curves and adjustable intrinsic gain up to 4, and exhibits unprecedented current stability in temperature range of 15–400 K. The vertical device operation can be optimized with the capacitive coupling in the device geometry. The semiconductor-less switching resolves the long-standing issue of temperature-dependent device performance, thereby extending the potential of 2D van der Waals devices to applications in extreme environments.
Highlights
Semiconductors have long been perceived as a prerequisite for solid-state transistors
To control ballistic transport adequately, we considered two modes by which current can tunnel through either vacuum or insulator channels: (1) direct tunneling (DT), which most graphene tunneling devices use for switching, and (2) field emission (FE), which has been rarely explored
Former graphenebased tunneling or lateral devices based on density of states (DOS)-dependent channel current have ION/IOFF ratios of ~10, which is a physical limit imposed by the fact that the charge density modulation is limited to 100 at room temperature[37]
Summary
Semiconductors have long been perceived as a prerequisite for solid-state transistors. Transition metal dichalcogenide-based FETs have shown ION/IOFF values of up to 108 using their bandgaps, but their carrier mobilities remain at ~20% of that of Si7 These inherent limitations can be resolved by using vertical van der Waals heterostructures and work function modulation of graphene as a switching principle[13]. Bipolar junction transistor-like devices have been investigated, where graphene was used as a base material, called as graphene-base transistor[26,27,28,29,30] The switching in such devices does not rely on the thermally generated charge of semiconductors, but semiconductors are still crucial elements required to achieve efficient switching. These 2D devices have the same limitations as conventional semiconductor devices: scattering-limited carrier mobility and temperature-dependent device performance
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