Localized tail state distribution and hopping transport in ultrathin zinc-tin-oxide thin film transistor

Li, Jeng Ting; Liu, Li Chih; Chen, Jen‐Sue; Jeng, Jiann Shing; Liao, Po Yung; Chiang, Hsiao Cheng; Chang, Ting Chang; Nugraha, Mohamad Insan; Loi, Maria Antonietta

doi:10.1063/1.4973992

Cited by 17 publications

(3 citation statements)

References 16 publications

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“…The localized states are filled as the charge density is increased after which the transport transitions to high mobility band transport so that ntr is a measure of the defect state density. This process has been observed in 2D semiconductors [35] and it contributes to the subthreshold rise in thin film transistors [36].…”

Section: Gate Voltage [V]mentioning

confidence: 82%

Ultrahigh mobility semiconducting epitaxial graphene on silicon carbide

Heer

Zhao

et al. 2023

Preprint

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Epigraphene, which is graphene that is epitaxially grown on a single crystal silicon carbide (SiC) substrate, was proposed as a path to extend Moore’s roadmap beyond silicon at the beginning of the millennium. Despite considerable progress, the lack of a bandgap in graphene and steps on the substrate continued to be roadblocks. Here we show a new method to produce millimeter scale step-free terraces covered with a graphene-like interface that is bonded to the SiC surface. This so-called buffer layer is found to be two-dimensional semiconducting epigraphene (SEG) with a 0.6 eV bandgap and a room temperature mobility exceeding 4000 cm2V-1s-1, which surpasses all current 2D single layer semiconductors by a factor of 10. A top-gated SEG field-effect transistor demonstrates an on-to-off ratio of 104 which is suitable for digital electronics. In addition, we also find that hydrogen intercalation converts SEG into a high-mobility semi-metallic epigraphene monolayer that can be seamlessly integrated with SEG. Centimeter scale mean free paths are observed in the epigraphene edge state of this quasi-freestanding monolayer, which is by a factor of 1000, the largest room temperature electronic mean free path observed in any material.

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Section: Gate Voltage [V]mentioning

confidence: 82%

Ultrahigh mobility semiconducting epitaxial graphene on silicon carbide

Heer

Zhao

et al. 2023

Preprint

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“…It is inferred that because the reaction of oxygen vacancies formation becomes more intense at high temperature (above 650 K), the concentration of oxygen vacancy increases significantly and the LAO/STO heterojunction is in an oxygen vacancies-rich state, which increases the system disorder degree and generates band-tail states at the bottom of the conduction band [22]. As shown in figure 3(b), electrons are thermally excited from the defect levels to a band-tail state first and then contribute to conductivity by jumping between band-tail states [22]. In this case, the conduction mechanism of LAO/STO heterojunction transferred to constant range hopping conduction.…”

Section: E D (Ev)mentioning

confidence: 99%

Electrical transport behavior of the oxygen vacancies-rich LaAlO₃/SrTiO₃ heterogeneous interface at high temperature

Luo,

Chen,

Wang

et al. 2023

J. Phys.: Condens. Matter

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Oxygen vacancy is one of the original mechanisms of the two-dimensional electron gas (2DEG) at the LaAlO3 (LAO) and SrTiO3 (STO) heterogeneous interface, and it has an important impact on the electrical properties of LAO/STO heterojunction. In this work, the LAO thin films were grown on the STO substrates by pulsed laser deposition, and the electrical transport behavior of the LAO/STO interface at high temperature and high vacuum were systematically studied. It was found that at high temperature and high vacuum, the oxygen vacancies-rich LAO/STO heterojunction would undergo a metal-insulator transition, and return to metal conductivity when the temperature is further increased. At this time, the conduction mechanism of the sample is drift mode and the thermal activation energy is 0.87 eV. While during the temperature decreasing, the conduction mechanism would transfer to hopping conduction with the thermal activation energy of 0.014 eV and the resistance would increase dramatically and present a completely insulated state. However, when the oxygen vacancies-rich sample is exposed to air, the resistance would gradually decrease and recover.

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“…Also, tail-states near the conduction band edge in the amorphous OS channels causes non-sharp change in the density of states (DOS), which degrades the subthreshold characteristics of the TFET [3]. Furthermore, it has been reported that a thin ZnSnO layer can include a high density of localized tail-states below E c [37]. Electrons trapped into the localized tail states in ZnSnO or other amorphous OS materials cannot directly flow in the OS channels [27], [38], but can contribute to the channel conduction by thermal activation into states higher than the mobility edge as shown in Fig.…”

Section: Physical Factors To Limit Sub-threshold Characteristics Omentioning

confidence: 99%

Fabrication and Electrical Characteristics of ZnSnO/Si Bilayer Tunneling Filed-Effect Transistors

Kato

Matsui

Tabata

et al. 2019

IEEE J. Electron Devices Soc.

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We demonstrate improvement of electrical characteristics of a bilayer tunneling field effect transistor (TFET) composed of an n-type zinc-tin-oxide (ZnSnO) channel with superior thickness uniformity and a p-type Si source. Careful optimization of the deposition condition of the ZnSnO layer leads to the significant improvement of the thickness uniformity thanks to its amorphous structure. It is promising to reduce the average sub-threshold swing (S.S.) of the bilayer TFET. The average S.S. of the amorphous ZnSnO/Si TFET is 87 mV/dec. in a gate voltage swing of 0.3 V, which is lower by 30% than that of the poly-crystalline ZnO/Si TFET with the rough surface. The minimum S.S. value of 80 mV/dec. in the ZnSnO/Si TFET is similar to that in the ZnO/Si TFET. Additionally, the ZnSnO/Si TFET has realized the increase in on-state current (I on) and the achieved I on of 1.7 μA/μm is approximately 8 times higher than that of the ZnO/Si TFET. We also found that the ZnSnO/Si TFET shows the stronger temperature dependence of both I on and S.S. than the ZnO/Si TFET. These differences in the electrical characteristics between ZnSnO and ZnO TFETs are discussed in terms of the amorphous and ploy-crystalline natures of the OS channels.

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Localized tail state distribution and hopping transport in ultrathin zinc-tin-oxide thin film transistor

Cited by 17 publications

References 16 publications

Ultrahigh mobility semiconducting epitaxial graphene on silicon carbide

Ultrahigh mobility semiconducting epitaxial graphene on silicon carbide

Electrical transport behavior of the oxygen vacancies-rich LaAlO₃/SrTiO₃ heterogeneous interface at high temperature

Fabrication and Electrical Characteristics of ZnSnO/Si Bilayer Tunneling Filed-Effect Transistors

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Localized tail state distribution and hopping transport in ultrathin zinc-tin-oxide thin film transistor

Cited by 17 publications

References 16 publications

Ultrahigh mobility semiconducting epitaxial graphene on silicon carbide

Ultrahigh mobility semiconducting epitaxial graphene on silicon carbide

Electrical transport behavior of the oxygen vacancies-rich LaAlO3/SrTiO3 heterogeneous interface at high temperature

Fabrication and Electrical Characteristics of ZnSnO/Si Bilayer Tunneling Filed-Effect Transistors

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Product

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Electrical transport behavior of the oxygen vacancies-rich LaAlO₃/SrTiO₃ heterogeneous interface at high temperature