High-speed black phosphorus field-effect transistors approaching ballistic limit

Abstract

As a strong candidate for future electronics, atomically thin black phosphorus (BP) has attracted great attention in recent years because of its tunable bandgap and high carrier mobility. Here, we show that the transport properties of BP device under high electric field can be improved greatly by the interface engineering of high-quality HfLaO dielectrics and transport orientation. By designing the device channels along the lower effective mass armchair direction, a record-high drive current up to 1.2 mA/μm at 300 K and 1.6 mA/μm at 20 K can be achieved in a 100-nm back-gated BP transistor, surpassing any two-dimensional semiconductor transistors reported to date. The highest hole saturation velocity of 1.5 × 107 cm/s is also achieved at room temperature. Ballistic transport shows a record-high 36 and 79% ballistic efficiency at room temperature and 20 K, respectively, which is also further verified by theoretical simulations.

Accuracy of Y-function methods for parameters extraction of two-dimensional FETs across different technologies

“…YFM also yields more similar values than YFM results to the ones obtained via a polynomial fit of the experimental [33 ] used for the extraction of the shorter MoS FETs: [22 ], and [23 ]. The upper limit reference value of given by a TLM characterisation for the shortest BPFET [25 ] at a bias close to the device saturation regime has been accomplished by YFM only.…”

“…Transfer characteristics of a 400 nm‐long MoS FET [24 ] b 100 nm‐long BPFET [25 ] c ‐long WeS FET [29 ] and d ‐long GFET [31 ]. Markers are experimental data and lines represent.…”

“…Accuracy and extracted parameters of 2D FET technologies. a Relation of the mean absolute error over of the extraction methodologies and b Ratios of channel to contact parameters of MoS FETs [4, 22–24 ], BPFETs [25–27 ], WeS FETs [28, 29 ] and GFETs [30–32 ]…”

Engineering valley quantum interference in anisotropic van der Waals heterostructures

“…The blue region is the elliptical insulator regime where Im{σ xx }, Im{σ yy } < 0, and the gray region is the elliptical metallic regime where Im{σ xx }, Im{σ yy } > 0. This chemical potential modification can be controlled via electrostatic gating [61][62][63] or chemical routes [64,65]. Doping provides an easy route to realize an actively tunable natural anisotropic environment for the monolayer TMDC, which enables one to modulate the valley coherence.…”

“…Figure 4(c) illustrates the color plot of the Q depending on h-BN thickness and chemical potential (μ). We have considered chemical potentials below 1 eV-a range which has been shown to be achievable with electrostatic doping techniques [61][62][63]67]. Figure 4(c) further shows that, as the thickness of hBN is increased, the interaction of the exciton with the surface plasmon modes decreases, yielding low coherence values.…”