Fabrication of stretchable MoS2 thin-film transistors using elastic ion-gel gate dielectrics

Pu, Jiang; Zhang, Yijin; Wada, Yuji; Wang, Jacob Tse-Wei; Li, Lain‐Jong; Iwasa, Yoshihiro; Takenobu, Taishi

doi:10.1063/1.4813311

Cited by 100 publications

(106 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[6][7][8][9][10][11][12] Besides in low power consumption electronics, devices based on MoS 2 , WS 2 , etc., also show potential for application in chemical sensing, light emitting, photo detecting, photovoltaics, and integrated flexible circuits. [13][14][15][16][17][18][19][20][21][22][23][24] Among these devices, the structure of metal-oxide-semiconductor (MOS) is mostly used. Charge trapping at the interface of the oxide and the semiconductor is common, 25,26 and MOS devices based on MoS 2 are not exceptional.…”

mentioning

confidence: 99%

Charge trapping at the MoS2-SiO2 interface and its effects on the characteristics of MoS2 metal-oxide-semiconductor field effect transistors

Guo

Wei

Shu

et al. 2015

Applied Physics Letters

227

189

View full text Add to dashboard Cite

The field effect transistors (FETs) based on thin layer MoS 2 often have large hysteresis and unstable threshold voltage in their transfer curves, mainly due to the charge trapping at the oxidesemiconductor interface. In this paper, the charge trapping and de-trapping processes at the SiO 2 -MoS 2 interface are studied. The trapping charge density and time constant at different temperatures are extracted. Making use of the trapped charges, the threshold voltage of the MoS 2 based metaloxide-semiconductor FETs is adjusted from 4 V to À45 V. Furthermore, the impact of the trapped charges on the carrier transport is evaluated. The trapped charges are suggested to give rise to the unscreened Coulomb scattering and/or the variable range hopping in the carrier transport of the MoS 2 sheet. 6-12 Besides in low power consumption electronics, devices based on MoS 2 , WS 2 , etc., also show potential for application in chemical sensing, light emitting, photo detecting, photovoltaics, and integrated flexible circuits. [13][14][15][16][17][18][19][20][21][22][23][24] Among these devices, the structure of metal-oxide-semiconductor (MOS) is mostly used. Charge trapping at the interface of the oxide and the semiconductor is common, 25,26 and MOS devices based on MoS 2 are not exceptional. 27 On one hand, charge trapping causes hysteresis and relaxation, hindering the stability of operational circuits, sensors, and photo detectors;28-30 on the other hand, charge trapping plays a key role in MoS 2 based multifunctional photoresponsive devices and flexible transparent multibit memory devices; [31][32][33][34] what is more, charge trapping offers a potential techniques for threshold voltage adjustment. 30 To better develop devices based on MoS 2 , understanding the charge trapping at the interface between the oxide and MoS 2 is necessary. SiO 2 is one of the most commonly used dielectric in MoS 2 based devices. Although trapped charges in the SiO 2 /Si substrate has been suggested to be the dominant source of potential fluctuations in MoS 2 field effect transistors (FETs), 35 there is no study on the charge trapping process for the SiO 2 in the MoS 2 based devices, and the effects of such trapped charges on the carrier transport is not clear so far. Here, the charge trapping and de-trapping processes at the MoS 2 -SiO 2 interface are studied, and their impact on the carrier transport is evaluated.MoS 2 devices were fabricated using cleaved MoS 2 sheets on SiO 2 /Si substrates (Figure 1(a)). To ensure the cleanness at the SiO 2 /MoS 2 interface, the process was done with extreme care. 36 The source and drain electrodes were patterned using electron beam lithography, followed by the deposition of Ti/ Au 5 nm/80 nm using electron beam evaporation. The heavily doped Si substrate was used as the back gate electrode. The thickness of the MoS 2 sheet is 3 nm, characterized by atomic force microscope (AFM), corresponding to three layers, as confirmed by the Raman spectrum. [36][37][38] The homogeneous contrast in the optical microscope and...

show abstract

mentioning

confidence: 99%

Charge trapping at the MoS2-SiO2 interface and its effects on the characteristics of MoS2 metal-oxide-semiconductor field effect transistors

Guo

Wei

Shu

et al. 2015

Applied Physics Letters

227

189

View full text Add to dashboard Cite

show abstract

“…[42,43] The low glass transition temperature of flexible polymer substrates used for the realization of such devices makes temperature a critical process parameter. [42,43] The low glass transition temperature of flexible polymer substrates used for the realization of such devices makes temperature a critical process parameter.…”

Section: D Semiconductorsmentioning

confidence: 99%

Air and Water‐Stable n‐Type Doping and Encapsulation of Flexible MoS₂ Devices with SU8

Kung

Hosseini

Dumcenco

et al. 2018

Adv Elect Materials

View full text Add to dashboard Cite

a high fracture strain of at least 10% [10] make MoS 2 and other 2D semiconductors good candidates for applications in flexible electronic devices and circuits. [11] However, several technical challenges need to be overcome before flexible devices based on 2D materials become widely available. Among them, a stable and controllable doping method that is compatible with flexible substrates and low processing temperatures should be developed. Strategies based on exposure to plasma, intercalation, and implantation were only demonstrated on multilayer MoS 2 [12][13][14] which is less interesting for optoelectronic applications due to its indirect bandgap. Substitutional doping with, for example, rhenium or niobium during CVD growth result in doping levels that cannot be modified after growth and are difficult to implement locally and selectively. [15,16] Chemical doping on the other hand, can be easily implemented due to the large surface to volume ratio of 2D materials. [17] Various molecular surface doping methods based on wet chemical treatment have been widely explored, but most of them are not air-stable and are difficult to control. [18][19][20][21] While doping strategies based on functionalizing 2D materials with noble metal nanoparticles offer air stability, they do not result in good uniformity. [22,23] Stable and controllable doping could be achieved using Cs 2 CO 3 thin films by varying the film thickness [24] or phosphorus silicate glass (PSG) substrates through thermal and optical activation; [25] however, brittle Cs 2 CO 3 films and PSG substrates are not suitable for flexible electronics. So far, a practical technique for achieving air-stable and controllable doping of MoS 2 using materials and processes that are compatible with flexible electronics is missing.An effective encapsulation layer with good gas barrier performance is another key enabler for flexible devices based on MoS 2 and other 2D semiconductors. It is well known that the performance of MoS 2 FETs degrades in air due to surface adsorption of O 2 and H 2 O. [26][27][28] Al 2 O 3 , HfO 2 , and other high-κ inorganic dielectrics have been commonly used as encapsulation layers for layered 2D devices. [2,29] However, their brittleness makes them undesirable for applications in flexible electronics, where the encapsulation layer usually experiences the highest strain under bending. Hexagonal boron nitride, a layered insulating material, is a promising candidate for encapsulation of other 2D materials due to the clean and smooth interface free of dangling bonds, but encapsulation is performed using a material transfer process which has so far been restricted to laboratory scale. [30][31][32] Favorable mechanical and electrical properties motivate the use of 2D semiconductors in flexible electronic devices. One of the main challenges here is the absence of a practical doping strategy which should provide air-stable, tunable doping levels in a process with a low thermal budget. Here, it is shown that SU8, an epoxy-based photoresist, can be used ...

show abstract

“…To exclude the grain boundaries induced relaxation to the applied strain, 22 the graphene samples used in our work were grown on copper foil by chemical vapor deposition (CVD) method with large grains; 23 they were confirmed to be monolayer by Raman spectroscopy. 24 The optical image of a typical grain is shown in Figure 3(a), with the size of approximately 600 lm, much larger than the region scanned by KPFM.…”

mentioning

confidence: 99%

Tuning the graphene work function by uniaxial strain

Tang

Sun

et al. 2015

Applied Physics Letters

View full text Add to dashboard Cite

Forming good metal/graphene contact is of significance in making graphene devices, while tuning the graphene work function is a valid approach to decrease the contact barrier and then achieve electrodes with low contact resistance. A strain device has been fabricated to apply uniaxial strain to graphene grown by chemical vapor deposition method, and Kelvin probe force microscopy was used to measure the work function of the graphene under strain. The work function of the graphene is found to increase as strain increases. By applying a uniaxial strain of 7%, the work function can be adjusted as large as 0.161 eV. Such a result can be explained by strain induced increase of the density of states in graphene.

show abstract

Fabrication of stretchable MoS2 thin-film transistors using elastic ion-gel gate dielectrics

Cited by 100 publications

References 41 publications

Charge trapping at the MoS2-SiO2 interface and its effects on the characteristics of MoS2 metal-oxide-semiconductor field effect transistors

Charge trapping at the MoS2-SiO2 interface and its effects on the characteristics of MoS2 metal-oxide-semiconductor field effect transistors

Air and Water‐Stable n‐Type Doping and Encapsulation of Flexible MoS₂ Devices with SU8

Tuning the graphene work function by uniaxial strain

Contact Info

Product

Resources

About

Fabrication of stretchable MoS2 thin-film transistors using elastic ion-gel gate dielectrics

Cited by 100 publications

References 41 publications

Charge trapping at the MoS2-SiO2 interface and its effects on the characteristics of MoS2 metal-oxide-semiconductor field effect transistors

Charge trapping at the MoS2-SiO2 interface and its effects on the characteristics of MoS2 metal-oxide-semiconductor field effect transistors

Air and Water‐Stable n‐Type Doping and Encapsulation of Flexible MoS2 Devices with SU8

Tuning the graphene work function by uniaxial strain

Contact Info

Product

Resources

About

Air and Water‐Stable n‐Type Doping and Encapsulation of Flexible MoS₂ Devices with SU8