Surface State Engineering of Metal/MoS<sub>2</sub>Contacts Using Sulfur Treatment for Reduced Contact Resistance and Variability

Bhattacharjee, Shubhadeep; Ganapathi, K.; Nath, Digbijoy N.; Bhat, Navakanta

doi:10.1109/ted.2016.2554149

Cited by 47 publications

(42 citation statements)

References 43 publications

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“…All electrical measurements reported in this work (except temperature‐dependent measurements) were made under ambient conditions. The “control FETs” (samples without vacancy engineering) demonstrated clear n‐type behavior, as commonly reported, with I on / I off ≈ 10 5 (Figure b). The n‐type behavior observed in MoS 2 despite use of high‐work function metal contacts is due to Fermi level pinning near the conduction band, as explored in our previous work .…”

Section: Resultssupporting

confidence: 78%

“…The “control FETs” (samples without vacancy engineering) demonstrated clear n‐type behavior, as commonly reported, with I on / I off ≈ 10 5 (Figure b). The n‐type behavior observed in MoS 2 despite use of high‐work function metal contacts is due to Fermi level pinning near the conduction band, as explored in our previous work . By contrast, the samples with vacancy engineering demonstrated a complete flip in carrier polarity, with a significant hole current (Figure c).…”

Section: Resultssupporting

confidence: 78%

“…Few‐layer MoS 2 with an indirect bandgap of 1.2 eV, close to that of silicon, is one of the most promising 2D material for electronic and optoelectronic applications . Exfoliated MoS 2 is naturally n‐type, possibly due to “S” vacancies; and the Fermi level of MoS 2 is pinned near the conduction band minimum, making hole transport in MoS 2 a significant challenge . Several techniques, such as chemical/molecular treatment, inserting a hole injector between metal/semiconductor, plasma treatment, etc.…”

Section: Introductionmentioning

confidence: 99%

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Hole Injection and Rectifying Heterojunction Photodiodes through Vacancy Engineering in MoS₂

Bhattacharjee

Vatsyayan

Ganapathi

et al. 2019

Adv Elect Materials

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The lack of techniques for counter doping in two dimensional (2D) semiconductors has hindered the development of p/n junctions, which are the basic building blocks of electronic devices. In this work, low‐energy argon ions are used to create sulfur vacancies and are subsequently “filled” with oxygen to create p‐doped MoS2−xOx. The incorporation of oxygen into the MoS2 lattice and hence band‐structure modification reveal the nature of the p‐type doping. These changes are validated by X‐ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, Raman spectroscopy, and photoluminescence measurements combined with density functional theory calculations. Electrical measurements reveal a complete flip in carrier polarity from n‐type to p‐type, which is further examined using temperature‐dependent transport measurements. The enhancement of p‐field‐effect transistor characteristics is facilitated by employing top‐gated transistors and area‐selective vacancy engineering only in the contact regions. Finally, on the same flake, an in‐plane MoS2 (n)/MoS2−xOx (p) type‐I (straddling) heterojunction with rectifying behavior and excellent broadband photoresponse is demonstrated and explained using band diagrams. The spatial/metallurgical abruptness (<100 nm) of the heterojunctions is ascertained using Raman mapping. This process of vacancy engineering, which enables air‐stable, area‐selective, controlled, CMOS‐compatible doping of 2D semiconductors is envisioned to open new vistas in the development of high‐performance electronic and optoelectronic devices.

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Section: Resultssupporting

confidence: 78%

Section: Resultssupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

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Hole Injection and Rectifying Heterojunction Photodiodes through Vacancy Engineering in MoS₂

Bhattacharjee

Vatsyayan

Ganapathi

et al. 2019

Adv Elect Materials

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“…Forming gas annealing could be another effective way to passivate Dit and enhance the MoS2 device performance (due to lowering of the SS and increase in the µFE) as shown by both Bolshakov et al [300,301] and Young et al [302]. [303]. The sulfur-treated devices showed consistent Ohmic behavior with good current saturation, reduced SBHs and R C as opposed to untreated reference samples that showed variable contact behavior (ranging from Schottky to Ohmic) with poor current saturation.…”

Section: Engineering Structural Defects Interface Traps and Surface mentioning

confidence: 89%

Progress in Contact, Doping and Mobility Engineering of MoS2: An Atomically Thin 2D Semiconductor

et al. 2018

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Atomically thin molybdenum disulfide (MoS2), a member of the transition metal dichalcogenide (TMDC) family, has emerged as the prototypical two-dimensional (2D) semiconductor with a multitude of interesting properties and promising device applications spanning all realms of electronics and optoelectronics. While possessing inherent advantages over conventional bulk semiconducting materials (such as Si, Ge and III-Vs) in terms of enabling ultra-short channel and, thus, energy efficient field-effect transistors (FETs), the mechanically flexible and transparent nature of MoS2 makes it even more attractive for use in ubiquitous flexible and transparent electronic systems. However, before the fascinating properties of MoS2 can be effectively harnessed and put to good use in practical and commercial applications, several important technological roadblocks pertaining to its contact, doping and mobility (µ) engineering must be overcome. This paper reviews the important technologically relevant properties of semiconducting 2D TMDCs followed by a discussion of the performance projections of, and the major engineering challenges that confront, 2D MoS2-based devices. Finally, this review provides a comprehensive overview of the various engineering solutions employed, thus far, to address the all-important issues of contact resistance (RC), controllable and area-selective doping, and charge carrier mobility enhancement in these devices. Several key experimental and theoretical results are cited to supplement the discussions and provide further insight.

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“…2(b), I D -V D indicates a non-linear behavior preanneal and more linear behavior post-anneal, suggesting that annealing also has a beneficial effect on the contacts, not just the dielectric, potentially removing the need for sulfur passivation treatments. [24][25][26] It is noted that with back-gate devices, proper C OX extraction from C-V measurements is nearly impossible due to the high capacitance resulting from the large area of the source/drain pads that dwarf the MoS 2 gate channel capacitance, nor would it be appropriate to extract D it using the subthreshold slope expression due to the uncertainty in C OX and C bulk. 19,27 With parameters such as the field effect mobility (l FE ) reliant on C OX for proper extraction, the proper device evaluation of the back-gate FET is limited, especially since its applicability to current CMOS technology is essentially non-existent.…”

mentioning

confidence: 99%

Improvement in top-gate MoS2 transistor performance due to high quality backside Al2O3 layer

Bolshakov

Zhao

Azcatl

et al. 2017

Applied Physics Letters

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A high quality Al2O3 layer is developed to achieve high performance in top-gate MoS2 transistors. Compared with top-gate MoS2 field effect transistors on a SiO2 layer, the intrinsic mobility and subthreshold slope were greatly improved in high-k backside layer devices. A forming gas anneal is found to enhance device performance due to a reduction in the charge trap density of the backside dielectric. The major improvements in device performance are ascribed to the forming gas anneal and the high-k dielectric screening effect of the backside Al2O3 layer. Top-gate devices built upon these stacks exhibit a near-ideal subthreshold slope of ∼69 mV/dec and a high Y-Function extracted intrinsic carrier mobility (μo) of 145 cm2/V·s, indicating a positive influence on top-gate device performance even without any backside bias.

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Surface State Engineering of Metal/MoS₂Contacts Using Sulfur Treatment for Reduced Contact Resistance and Variability

Cited by 47 publications

References 43 publications

Hole Injection and Rectifying Heterojunction Photodiodes through Vacancy Engineering in MoS₂

Hole Injection and Rectifying Heterojunction Photodiodes through Vacancy Engineering in MoS₂

Progress in Contact, Doping and Mobility Engineering of MoS2: An Atomically Thin 2D Semiconductor

Improvement in top-gate MoS2 transistor performance due to high quality backside Al2O3 layer

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Surface State Engineering of Metal/MoS2Contacts Using Sulfur Treatment for Reduced Contact Resistance and Variability

Cited by 47 publications

References 43 publications

Hole Injection and Rectifying Heterojunction Photodiodes through Vacancy Engineering in MoS2

Hole Injection and Rectifying Heterojunction Photodiodes through Vacancy Engineering in MoS2

Progress in Contact, Doping and Mobility Engineering of MoS2: An Atomically Thin 2D Semiconductor

Improvement in top-gate MoS2 transistor performance due to high quality backside Al2O3 layer

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Product

Resources

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Surface State Engineering of Metal/MoS₂Contacts Using Sulfur Treatment for Reduced Contact Resistance and Variability

Hole Injection and Rectifying Heterojunction Photodiodes through Vacancy Engineering in MoS₂

Hole Injection and Rectifying Heterojunction Photodiodes through Vacancy Engineering in MoS₂