HfS2

/Tag: HfS2

Efficient charge separation and visible-light response in bilayer HfS2-based van der Waals heterostructures

2018-05-29T12:56:00+00:00 May 29th, 2018|Categories: Publications|Tags: , |

RSC Adv., 2018, 8,18889-18895DOI: 10.1039/C8RA03047B, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.Biao Wang, Xukai Luo, Junli Chang, Xiaorui Chen, Hongkuan Yuan, Hong ChenIn this work, we employ hybrid density functional theory to investigate HfS2-based

Published in: "RSC Advances".

Efficient charge separation and visible-light response in bilayer HfS2-based van der Waals heterostructures

2018-05-24T10:29:51+00:00 May 24th, 2018|Categories: Uncategorized|Tags: , |

RSC Adv., 2018, 8,18889-18895DOI: 10.1039/C8RA03047B, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.Biao Wang, Xukai Luo, Junli Chang, Xiaorui Chen, Hongkuan Yuan, Hong ChenIn this work, we employ hybrid density functional theory to investigate HfS2-based van der Waals (vdW) heterojunctions for highly efficient photovoltaic and photocatalytic applications.The content of this RSS Feed (c) The Royal Society of Chemistry

Strain-engineered inverse charge-funnelling in layered semiconductors. (arXiv:1801.09434v1 [physics.app-ph])

2018-01-30T19:58:54+00:00 January 30th, 2018|Categories: Publications|Tags: |

The control of charges in a circuit due to an external electric field is ubiquitous to the exchange, storage and manipulation of information in a wide range of applications, from electronic circuits to synapses in neural cells. Conversely, the ability to grow clean interfaces between materials has been a stepping stone for engineering built-in electric fields largely exploited in modern photovoltaics and opto-electronics. The emergence of atomically thin semiconductors is now enabling new ways to attain electric fields and unveil novel charge transport mechanisms. Here, we report the first direct electrical observation of the inverse charge-funnel effect enabled by deterministic and spatially resolved strain-induced electric fields in a thin sheet of HfS2. We demonstrate that charges driven by these spatially varying electric fields in the channel of a phototransistor lead to a 350% enhancement in the responsivity. These findings could enable the informed design of highly efficient photovoltaic cells.

Published : "arXiv Mesoscale and Nanoscale Physics".

Space-Confined Chemical Vapor Deposition Synthesis of Ultrathin HfS2 Flakes for Optoelectronic Application

2017-08-15T08:29:07+00:00 August 15th, 2017|Categories: Publications|Tags: |

Due to the predicted excellent electronic properties superior to group VIB (Mo and W) transition metal dichalcogenides (TMDs), group IVB TMDs have enormous potential in nanoelectronics. Here, the synthesis of ultrathin HfS2 flakes via space-confined chemical vapor deposition, realized by an inner quartz tube, is demonstrated. Moreover, the effect of key growth parameters including the dimensions of confined space and deposition temperature on the growth behavior of products is systematically studied. Typical as-synthesized HfS2 is a hexagonal-like flake with a smallest thickness of ≈1.2 nm (bilayer) and an edge size of ≈5 µm. The photodetector based on as-synthesized HfS2 flakes demonstrates excellent optoelectronic performance with a fast photoresponse time (55 ms), which is attributed to the high-quality crystal structure obtained at a high deposition temperature and the ultraclean interface between HfS2 and the mica substrate. With such properties HfS2 holds great potential for optoelectronics applications. High-quality ultrathin HfS2 flakes are synthesized for the first time via an improved chemical vapor deposition method introducing a confined space, which is employed to construct a precursor growth environment that is stable and precisely tunable regarding reactant concentrations. The photodetector based on the HfS2 flake shows a fast response time of 55 ms.

Published in: "Advanced Functional Materials".

Van der Waals Epitaxial Growth of Atomic Layered HfS2 Crystals for Ultrasensitive Near-Infrared Phototransistors

2017-06-22T07:21:48+00:00 June 22nd, 2017|Categories: Publications|Tags: , |

As a member of the group IVB transition metal dichalcogenides (TMDs) family, hafnium disulfide (HfS2) is recently predicted to exhibit higher carrier mobility and higher tunneling current density than group VIB (Mo and W) TMDs. However, the synthesis of high-quality HfS2 crystals, sparsely reported, has greatly hindered the development of this new field. Here, a facile strategy for controlled synthesis of high-quality atomic layered HfS2 crystals by van der Waals epitaxy is reported. Density functional theory calculations are applied to elucidate the systematic epitaxial growth process of the S-edge and Hf-edge. Impressively, the HfS2 back-gate field-effect transistors display a competitive mobility of 7.6 cm2 V−1 s−1 and an ultrahigh on/off ratio exceeding 108. Meanwhile, ultrasensitive near-infrared phototransistors based on the HfS2 crystals (indirect bandgap ≈1.45 eV) exhibit an ultrahigh responsivity exceeding 3.08 × 105 A W−1, which is 109-fold higher than 9 × 10−5 A W−1 obtained from the multilayer MoS2 in near-infrared photodetection. Moreover, an ultrahigh photogain exceeding 4.72 × 105 and an ultrahigh detectivity exceeding 4.01 × 1012 Jones, superior to the vast majority of the reported 2D-materials-based phototransistors, imply a great promise in TMD-based 2D electronic and optoelectronic applications. A facile strategy for the synthesis of high-quality monolayer HfS2 crystals by van der Waals epitaxy is reported. Ultrasensitive near-infrared phototransistors based on the HfS2 crystals exhibit an ultrahigh responsivity 3.08 × 105 A W−1, and an ultrahigh detectivity exceeding 4.01 × 1012 Jones, superior to most 2D materials-based phototransistors.

Published in: "Advanced Materials".

Ultrasensitive Phototransistors Based on Few-Layered HfS2

2015-10-26T09:13:14+00:00 October 26th, 2015|Categories: Publications|Tags: |

An ultrathin HfS2-based ultrasensitive phototransistor is systematically studied. Au-contacted HfS2 phototransistors with ideal thickness ranging from 7 to 12 nm exhibit a high on/off ratio of ca. 107, ultrahigh photoresponsivity over 890 A W−1, and photogain over 2300. Moreover, the response time is strongly dependent on the back-gate voltage and shows a reverse trend for Au and Cr metals.

Published in: "Advanced Materials".

Modeling of anisotropic two-dimensional materials monolayer HfS2 and phosphorene metal-oxide semiconductor field effect transistors

2016-10-15T11:47:56+00:00 June 1st, 2015|Categories: Publications|Tags: , |

By Jiwon Chang Ballistic transport characteristics of metal-oxide semiconductor field effect transistors (MOSFETs) based on anisotropic two-dimensional materials monolayer HfS2 and phosphorene are explored through quantum transport simulations. We focus on the effects of the channel crystal orientation and the channel length scaling on device performances. Especially, the role of degenerate conduction band …read more

Published in: Journal of Applied Physics

Few Layer HfS2 FET. (arXiv:1505.07970v1 [cond-mat.mes-hall])

2016-10-15T11:48:10+00:00 June 1st, 2015|Categories: Publications|Tags: , |

By Toru Kanazawa, Tomohiro Amemiya, Atsushi Ishikawa, Vikrant Upadhyaya, Kenji Tsuruta, Takuo Tanaka, Yasuyuki Miyamoto 2D materials are expected to be favorable channel materials for field-effect
transistor (FET) with extremely short channel length because of their superior
immunity to short-channel effects (SCE). Graphene, which is the most famous 2D
material, has no bandgap without additional techniques and this property is
major hindrance in reducing the drain leakage. Therefore, 2D …read more

Published in: arXiv Material Science

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