Transport properties of ultrathin black phosphorus on hexagonal boron nitride

Doganov, Rostislav A.; Koenig, Steven P.; Yeo, Ye; Watanabe, Kenji; Taniguchi, Takashi; Özyilmaz, Barbaros

doi:10.1063/1.4913419

Cited by 99 publications

(85 citation statements)

References 23 publications

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“…The first point suggests that there is no electronic-structure downside to hBN-encapsulation, which is already known to protect BP from environmental interactions. 29,31,32 The second conclusion is especially relevant for optoelectronics, as it implies that hBN-spaced BP stacks have the same light-absorption properties as monolayer BP, with the essential difference that more photons are absorbed due to the increased thickness. Finally, since the operation of BP/hBN/BP as a TFET is based on quantum tunneling, instead of thermionic excitation of carriers, we encounter negative differential resistance (NDR) peaks 33 with peak-to-valley ratios (PVRs) comparable to those predicted for TMDC TFETs, 34 as well as subthreshold swings below the minimum theoretical limit for conventional field effect transistors.…”

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confidence: 99%

Multipurpose Black-Phosphorus/hBN Heterostructures

2016

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Black phosphorus (BP) has recently emerged as a promising semiconducting twodimensional material. However, its viability is threatened by its instability in ambient conditions, and by the significant decrease of its band gap in multilayers. We show that one could solve all the aforementioned problems by interfacing BP with hexagonal boron nitride (hBN). To this end, we simulate large, rotated hBN/BP interfaces using linear-scaling density functional theory (DFT). We predict that hBN-encapsulation preserves the main electronic properties of the BP monolayer, while hBN spacers can be used to counteract the band gap reduction in stacked BP. Finally, we propose a model for a tunneling field effect transistor (TFET) based on hBN-spaced BP bilayers.Such BP TFETs would sustain both low-power and fast-switching operations, including negative differential resistance behaviour with peak-to-valley ratios of the same order of magnitude as those encountered in transition metal dichalcogenide TFETs.1 Keywords 2D heterostructures; tunneling transistor; linear-scaling DFT; electric fields Since its inception, the two-dimensional (2D) material community has switched focus several times between different materials, aiming to satisfy different technological requirements. For instance, the lack of a band gap in graphene caused an increased interest in semiconducting transition metal dichalcogenides (TMDCs). While their many qualities have enabled their remarkable success in semiconductor electronics, 1,2 spintronics, 3 and optoelectronics, 2,4 the associated flaws of TMDCs are also of concern. Most notably, they only exhibit a direct band gap when in monolayer form, 5 the carrier mobilities are far smaller than those encountered in graphene, and their large band gap implies that the infrared (IR) spectrum cannot be harnessed by TMDC optoelectronics.In this context, the spotlight has recently shifted to layered black phosphorus (BP), 6,7 a material which rectifies the most important shortcomings of TMDCs. The band gap of BP is direct even in stacked forms, and its value changes significantly with the number of layers: from 0.3 eV in bulk to 1.5-2.0 eV for the monolayer. 8,9 This range of values allows BP to

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confidence: 99%

Multipurpose Black-Phosphorus/hBN Heterostructures

2016

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“…3. Theoretical and experimental studies have shown that metastable oxygen adsorbed on the surface of few-layer BP will lead to p -doping upon exposure to air, but the adsorption can be removed during the annealing [13, 14], then leading to a reduction in p -doping. In Fig.…”

Section: Resultsmentioning

confidence: 99%

The Role of Air Adsorption in Inverted Ultrathin Black Phosphorus Field-Effect Transistors

Chen

Feng

et al. 2016

Nanoscale Res Lett

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Few-layer black phosphorus (BP) attracts much attention owing to its high mobility and thickness-tunable band gap; however, compared with the commonly studied transition metal dichalcogenides (TMDCs), BP has the unfavorable property of degrading in ambient conditions. Here, we propose an inverted dual gates structure of ultrathin BP FET to research the air adsorption on BP. In fabrication process of back-gate BP FET, BP was transferred directly onto a wafer covered with electrodes. Thus, we can exclude the BP degradation during the process of electrodes fabrication, such as electron beam lithography (EBL) and thermal evaporation process. Furthermore, without any electrode covering BP, BP could be in full contact with the air; then the accurate effect of the air adsorption on BP can be researched in detail. The results clearly show that annealing can remove the p-doping resulted from the metastable oxygen adsorbed on the surface of BP, but the adsorption can be restored in a few hours exposure. In addition, both back and top gate inverted BP FETs exhibit a favorable performance. Therefore, this inverted structure is also an optional structure to reduce the influence of the instability of BP devices.

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“…[28] Nevertheless, their results appear slightly ambiguous because the contact and channel resistances are not separately claimed. [29] In this letter, we report the fundamental electrical degradation mechanism of BP transistors in terms of the contact and channel resistances, respectively.…”

Section: Introductionmentioning

confidence: 96%