Variable range hopping electric and thermoelectric transport in anisotropic black phosphorus

Liu, Huili; Choe, Hwan Sung; Chen, Yabin; Suh, Joonki; Ko, Changhyun; Tongay, Sefaattin; Wu, Junqiao

doi:10.1063/1.4985333

Cited by 45 publications

(33 citation statements)

References 32 publications

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“…Another possible mechanism for the super-linear I – V behavior might be hopping transport in the BP channel which occurs due to the charge traps along the channel-dielectric interface 24 . In hopping transports, trapped charges are released with increasing temperature and electric field, leading to an increase in conductivity with bias.…”

Section: Resultsmentioning

confidence: 99%

“…In hopping transports, trapped charges are released with increasing temperature and electric field, leading to an increase in conductivity with bias. In fact, a 2D Mott’s variable range hopping mechanism was recently reported as describing the carrier transport mechanism for SiO 2 -supported thermoelectric BP devices 24 , 25 . However, the observed hopping transport occurs at low electric fields where the energy difference between the trap states and charge carriers is very large, while this difference becomes negligible at the large field values where energetic carriers can easily surmount the trap sites.…”

Section: Resultsmentioning

confidence: 99%

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Impact ionization by hot carriers in a black phosphorus field effect transistor

et al. 2018

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The strong Coulombic interactions in miniaturized structures can lead to efficient carrier multiplication, which is essential for many-body physics and design of efficient photonic devices beyond thermodynamic conversion limits. However, carrier multiplication has rarely been realized in layered semiconducting materials despite strong electronic interactions. Here, we report the experimental observation of unusual carrier multiplication in a multilayer black phosphorus device. Electric field-dependent Hall measurements confirm a substantial increase of carrier density in multilayer black phosphorus channel, which is attributed to the impact ionization by energetic carriers. This mechanism relies on the generation of self-heating induced charge carriers under the large electric field due to competition between electron–electron and electron–phonon interactions in the direct and narrow band gap (0.3 eV) of the multilayer black phosphorus. These findings point the way toward utilization of carrier multiplication to enhance the performance of electronics and optoelectronics devices based on two-dimensional materials.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Impact ionization by hot carriers in a black phosphorus field effect transistor

et al. 2018

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“…Details of device fabrication and measurements were published previously. 11,12 Figure 2c shows a set of a-axis-oriented TiS 3 nanoribbons of length ~ 40 m and width varying from ~0.5 to ~2 m, e-beam lithographically patterned from a single flake with a thickness of 100 nm. These individual nanoribbons were carefully dry-transferred onto the two suspended micro-pads to bridge them.…”

Section: Abstract: Titanium Trisulfide In-plane Anisotropy Optical mentioning

confidence: 99%

Extreme In-Plane Thermal Conductivity Anisotropy in Titanium Trisulfide Caused by Heat-Carrying Optical Phonons

Liu

et al. 2020

Nano Lett.

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High in-plane anisotropies arise in layered materials with large structural difference along different in-plane directions. We report an extreme case in layered TiS 3 , which features tightly bonded atomic chains along the b-axis direction, held together by weaker, interchain bonding along the a-axis direction. Experiments show thermal conductivity along the chain twice as high as between the chain, an in-plane anisotropy higher than any other layered materials measured to date. We found that in contrast to most other materials, optical phonons in TiS 3 conduct an unusually high portion of heat (up to 66% along the b-axis direction). The large dispersiveness of optical phonons along the chains, contrasted to many fewer dispersive optical phonons perpendicular to the chains, is the primary reason for the observed high anisotropy in thermal conductivity. The finding discovers materials with unusual thermal conduction mechanism, as well as provides new material platforms for potential heat-routing or heat-managing devices.

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“…Interestingly, the anisotropic behavior of thermal conductivity was the opposite of that of electrical conductivity . Based on these observations, anisotropic thermopower measurements were also observed, as shown in Figure 6d,e . Notably, the electrical conductivity and the Seebeck coefficient indicated the same trends, which gives significant insight to improve the thermoelectric performance of black phosphorus.…”

Section: Thermoelectric Properties Of Single‐crystalline and Polycrysmentioning

confidence: 61%

“…d,e) Temperature dependence of electrical conductivity d) and the Seebeck coefficient e) for both the armchair (red) and zigzag (blue) directions. Reproduced with permission . Copyright 2015, American Institute of Physics.…”

Section: Thermoelectric Properties Of Single‐crystalline and Polycrysmentioning

confidence: 99%

2D Materials for Large‐Area Flexible Thermoelectric Devices

Kanahashi

Takenobu

2019

Advanced Energy Materials

178

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The rapid development of the concept of the “Internet of Things (IoT)” requires wearable devices with maintenance‐free batteries, and thermoelectric energy conversion based on large‐area flexible materials has attracted much attention. Among large‐area flexible materials, 2D materials, such as graphene and related materials, are promising for thermoelectric applications due to their excellent transport properties and large power factors. In this Review, both single‐crystalline and polycrystalline 2D materials are surveyed using the experimental reports on thermoelectric devices of graphene, black phosphorus, transition metal dichalcogenides, and other 2D materials. In particular, their carrier‐density dependent thermoelectric properties and power factors maximized by Fermi level tuning techniques are focused. The comparison of the relevant performances between 2D materials and commonly used thermoelectric materials reveals the significantly enhanced power factors in 2D materials. Moreover, the current progress in thermoelectric module applications using large‐area 2D material thin films is summarized, which consequently offers great potential for the use of 2D materials in large‐area flexible thermoelectric device applications. Finally, important remaining issues and future perspectives, such as preparation methods, thermal transports, device designs, and promising effects in 2D materials, are discussed.

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Variable range hopping electric and thermoelectric transport in anisotropic black phosphorus

Cited by 45 publications

References 32 publications

Impact ionization by hot carriers in a black phosphorus field effect transistor

Impact ionization by hot carriers in a black phosphorus field effect transistor

Extreme In-Plane Thermal Conductivity Anisotropy in Titanium Trisulfide Caused by Heat-Carrying Optical Phonons

2D Materials for Large‐Area Flexible Thermoelectric Devices

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