Impact of Thickness on Contact Issues for Pinning Effect in Black Phosphorus Field‐Effect Transistors

Jiang, Bei; Zou, Xuming; Su, Jie; Liang, Jinghua; Wang, Jingli; Liu, Huijun; Feng, Li; Jiang, Cong; Wang, Rui; He, Jun; Liao, Lei

doi:10.1002/adfm.201801398

Cited by 47 publications

(51 citation statements)

References 47 publications

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“…45 The presence of Fermi level pinning has already been suggested and studied theoretically for few-layer bP, 46 and it has been as well investigated experimentally. 32 What is observed for bP 32 Fermi level pinning. 47,48 Since in our sample processing we introduced an oxygen plasma step, this could have modified the surface state density, changing the conditions at the interface.…”

Section: Contact Resistancementioning

confidence: 82%

“…Despite the interest in this topic, experimentally, up to now, just few studies on the contact resistance to bP were reported. 15,15,[30][31][32][33] Among them, a big focus is on the transition between unipolar and ambipolar behavior in bP. 15,31 Even if several metals were inspected, it is difficult to extract a consistent picture, given also the differences in sample fabrication techniques among the various studies, but most of all because of the high reactivity of bP, whose uncontrolled oxidation, hard to prevent, introduces a large uncertainty in the observed behavior.…”

Section: Introductionmentioning

confidence: 99%

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Ohmic contact engineering in few–layer black phosphorus: approaching the quantum limit

et al. 2020

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Achieving good quality Ohmic contacts to van der Waals materials is a challenge, since at the interface between metal and van der Waals material, different conditions can occur, ranging from the presence of a large energy barrier between the two materials to the metallization of the layered material below the contacts. In black phosphorus (bP), a further challenge is its high reactivity to oxygen and moisture, since the presence of uncontrolled oxidation can substantially change the behavior of the contacts. In this study, we investigate the influence of the metal used for the contacts to bP against the variability between different flakes and different samples, using three of the most used metals as contacts: Chromium, Titanium, and Nickel. Using the transfer length method, from an analysis of ten devices, both at room temperature and at low temperature, Ni results to be the best metal for Ohmic contacts to bP, providing the lowest 1 arXiv:1905.05649v1 [cond-mat.mes-hall]

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Section: Contact Resistancementioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Ohmic contact engineering in few–layer black phosphorus: approaching the quantum limit

et al. 2020

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“…The opposite phenomenon about the relationship of the I on / I off versus temperature was observed in Figure d. To further quantify the Schottky barrier between Cr/Te, it can be deduced by the equation

I_{ds} = A A^{*} T^{2} \exp (\frac{q normalΦ}{k_{B} T}) ([], 1 - normalexp (- \frac{q V_{ds}}{k_{normalB} T}))

where I ds is the current through the device, Φ is the Schottky barrier, q is the magnitude of the electron charge, T is the temperature, and V ds is 1 V. When V g is above V FB , thermally assisted tunneling current becomes dominating which leads to the nonlinear behavior . By contrast, the thermionic emission current predominates the current.…”

Section: Resultsmentioning

confidence: 98%

Hydrogen‐Assisted Growth of Ultrathin Te Flakes with Giant Gate‐Dependent Photoresponse

Zhang

Jiang

Suleiman

et al. 2019

Adv Funct Materials

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Tellurium (Te), as an elementary material, has attracted intense attention due to its potentially novel properties. However, it is still a great challenge to realize high-quality 2D Te due to its helical chain structure. Here, ultrathin Te flakes (5 nm) are synthesized via hydrogen-assisted chemical vapor deposition method. The density functional theory calculations and experiments confirm the growth mechanism, which can be ascribed to the formation of volatile intermediates increasing vapor pressure of the source and promoting the reaction. Impressively, the Te flake-based transistor shows high on/off ratio ≈10 4 , ultralow off-state current ≈8 × 10 −13 A, as well as a negligible hysteresis due to reducing thermally activated defects at 80 K. Moreover, Te-flake-based phototransistor demonstrates giant gate-dependent photoresponse: when gate voltage varies from −70 to 70 V, I on /I off is increased by ≈40-fold. The hydrogen-assisted strategy may provide a new approach for synthesizing other high quality 2D elementary materials.

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“…The device is p-type with an intrinsic resistance ~300 Ω. We note that the on/off ratio for the range of gate voltages shown is only ~15, which is typical of thicker BP FETs due to the relatively high conductance of the naturally doped bulk crystal and the small out-of-plane screening length 28,45,46 .…”

mentioning

confidence: 91%

Spectral Responsivity and Photoconductive Gain in Thin Film Black Phosphorus Photodetectors

et al. 2019

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We have fabricated black phosphorus photodetectors and characterized their full spectral responsivity. These devices, which are effectively in the bulk thin film limit, show broadband responsivity ranging from <400 nm to the ~3.8 µm bandgap. In the visible, an intrinsic responsivity >7 A/W can be obtained due to internal gain mechanisms. By examining the full spectral response, we identify a sharp contrast between the visible and infrared behavior.In particular, the visible responsivity shows a large photoconductive gain and gate-voltge dependence, while the infrared responsivity is nearly independent of gate voltage and incident light intensity under most conditions. This is attributed to a contribution from the surface oxide.In addition, we find that the polarization anisotropy in responsivity along armchair and zigzag directions can be as large as 10 3 and extends from the band edge to 500 nm. The devices were fabricated in an inert atmosphere and encapsulated by Al 2 O 3 providing stable operation for more than 6 months.

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Impact of Thickness on Contact Issues for Pinning Effect in Black Phosphorus Field‐Effect Transistors

Cited by 47 publications

References 47 publications

Ohmic contact engineering in few–layer black phosphorus: approaching the quantum limit

Ohmic contact engineering in few–layer black phosphorus: approaching the quantum limit

Hydrogen‐Assisted Growth of Ultrathin Te Flakes with Giant Gate‐Dependent Photoresponse

Spectral Responsivity and Photoconductive Gain in Thin Film Black Phosphorus Photodetectors

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