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Title: Transient hot-carrier dynamics and intrinsic velocity saturation in monolayer MoS2

Abstract

Drift velocity saturation (at some characteristic value,$$v_d^{sat}$$) is a critical process that limits the ultimate current-carrying capacity of semiconductors at high electric fields (~104 V/cm). With the recent emergence of two-dimensional (2D) semiconductors, there is a need to understand the manner in which velocity saturation is impacted when materials are thinned to the monolayer scale. Efforts to determine vsatd are typically hampered, however, by self-heating effects that arise from undesirable energy loss from the active 2D layer to the dielectric substrate that supports it. In this work, we explore this problem for an important 2D semiconductor, namely monolayer molybdenum disulfide (MoS2). By applying a strategy of rapid (nanosecond duration), single-shot, pulsing, we are able to probe the true hot-carrier dynamics in this material, free of the influence of self-heating of its SiO2 substrate. Our approach allows us to realize high current densities (~mA/μm) in the MoS2 layers, representing a significant enhancement over prior studies. We similarly infer values for the saturated drift velocity ($$v_d^{sat}$$ ~ 5-7 x 106 cm s-1) that are higher than those reported in earlier works, in which the influence of self-heating (and carrier injection into oxide traps) could not be excluded. In fact, our estimates for $$v_d^{sat}$$ are somewhat close to the ideal velocity expected for normal (parabolic) semiconductors. Lastly, since a proper knowledge of this parameter is essential to the design of active electronic and optoelectronic devices, the insight into velocity saturation provided here should provide useful guidance for such efforts.

Authors:
 [1];  [2];  [2];  [1];  [1];  [1];  [1];  [1];  [1];  [2];  [1]
  1. State Univ. of New York (SUNY), Buffalo, NY (United States)
  2. Stanford Univ., CA (United States)
Publication Date:
Research Org.:
State Univ. of New York (SUNY), Buffalo, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division
OSTI Identifier:
1593522
Grant/Contract Number:  
FG02-04ER46180
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review Materials
Additional Journal Information:
Journal Volume: 4; Journal Issue: 1; Journal ID: ISSN 2475-9953
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Nathawat, J., Smithe, K. K. H., English, C. D., Yin, S., Dixit, R., Randle, M., Arabchigavkani, N., Barut, B., He, K., Pop, E., and Bird, J. P. Transient hot-carrier dynamics and intrinsic velocity saturation in monolayer MoS2. United States: N. p., 2020. Web. doi:10.1103/PhysRevMaterials.4.014002.
Nathawat, J., Smithe, K. K. H., English, C. D., Yin, S., Dixit, R., Randle, M., Arabchigavkani, N., Barut, B., He, K., Pop, E., & Bird, J. P. Transient hot-carrier dynamics and intrinsic velocity saturation in monolayer MoS2. United States. https://doi.org/10.1103/PhysRevMaterials.4.014002
Nathawat, J., Smithe, K. K. H., English, C. D., Yin, S., Dixit, R., Randle, M., Arabchigavkani, N., Barut, B., He, K., Pop, E., and Bird, J. P. Fri . "Transient hot-carrier dynamics and intrinsic velocity saturation in monolayer MoS2". United States. https://doi.org/10.1103/PhysRevMaterials.4.014002. https://www.osti.gov/servlets/purl/1593522.
@article{osti_1593522,
title = {Transient hot-carrier dynamics and intrinsic velocity saturation in monolayer MoS2},
author = {Nathawat, J. and Smithe, K. K. H. and English, C. D. and Yin, S. and Dixit, R. and Randle, M. and Arabchigavkani, N. and Barut, B. and He, K. and Pop, E. and Bird, J. P.},
abstractNote = {Drift velocity saturation (at some characteristic value,$v_d^{sat}$) is a critical process that limits the ultimate current-carrying capacity of semiconductors at high electric fields (~104 V/cm). With the recent emergence of two-dimensional (2D) semiconductors, there is a need to understand the manner in which velocity saturation is impacted when materials are thinned to the monolayer scale. Efforts to determine vsatd are typically hampered, however, by self-heating effects that arise from undesirable energy loss from the active 2D layer to the dielectric substrate that supports it. In this work, we explore this problem for an important 2D semiconductor, namely monolayer molybdenum disulfide (MoS2). By applying a strategy of rapid (nanosecond duration), single-shot, pulsing, we are able to probe the true hot-carrier dynamics in this material, free of the influence of self-heating of its SiO2 substrate. Our approach allows us to realize high current densities (~mA/μm) in the MoS2 layers, representing a significant enhancement over prior studies. We similarly infer values for the saturated drift velocity ($v_d^{sat}$ ~ 5-7 x 106 cm s-1) that are higher than those reported in earlier works, in which the influence of self-heating (and carrier injection into oxide traps) could not be excluded. In fact, our estimates for $v_d^{sat}$ are somewhat close to the ideal velocity expected for normal (parabolic) semiconductors. Lastly, since a proper knowledge of this parameter is essential to the design of active electronic and optoelectronic devices, the insight into velocity saturation provided here should provide useful guidance for such efforts.},
doi = {10.1103/PhysRevMaterials.4.014002},
journal = {Physical Review Materials},
number = 1,
volume = 4,
place = {United States},
year = {Fri Jan 10 00:00:00 EST 2020},
month = {Fri Jan 10 00:00:00 EST 2020}
}

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