| Impact of intrinsic trap states on the electrical and optoelectronic behavior of ReS2 and ReSe2 |
Gyeong Deok Seo1,2, Gi Dan Shim1,2, Seung Yong Back1, Sungjune Park3, Hagyoul Bae4, TaeWan Kim1,2,5
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1Department of Intelligent Semiconductor Engineering, University of Seoul, Seoul 02504, Republic of Korea
22D Epi, Inc, 567 Baekje-Daero, Jeonju 54896, Republic of Korea
3School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon 16419 , Republic of Korea
4Department of Electronic Engineering , Jeonbuk National University , Jeonju 54896, Republic of Korea
5School of Advanced Fusion Studies, University of Seoul, Seoul 02504, Republic of Korea |
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Received: August 15, 2025; Revised: November 28, 2025 Accepted: December 6, 2025. Published online: January 12, 2026. |
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| ABSTRACT |
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Rhenium-based two-dimensional transition metal dichalcogenides, such as ReS2 and ReSe2, have attracted considerable interest for optoelectronic applications—including polarization-sensitive photodetectors—due to their weak interlayer coupling, strong in-plane anisotropy, and monolayer-like direct bandgaps. However, performance inconsistencies such as hysteresis, often induced by both intrinsic and extrinsic trap states, remain a challenge in TMD-based devices. In this study, we present a comparative analysis of the scattering mechanisms, hysteresis, and photoresponsivity (R) of ReS2 and ReSe2 phototransistors by examining their transfer characteristics under varying temperatures and illumination conditions. Trap-state distributions were systematically investigated using wavelength-resolved sub-bandgap illumination, which enables emission of carriers from deeper trap states. The ReS2 device exhibits electron–phonon scattering as the dominant transport mechanism, along with minimal hysteresis, attributed to a lower density of intrinsic traps with widely spaced trap states. In contrast, the ReSe2 device is characterized by charge-impurity scattering and pronounced hysteresis, arising from a higher trap density with closely spaced trap states. Additionally, ReSe2 displays a more gradual decline in the power-law exponent (γ) across a broader gate-voltage range and lower R compared to ReS2. These distinctions are linked to the higher formation energy of chalcogen vacancies in ReS2, which makes it more resistant to defect formation than ReSe2. |
| Key words:
ReS2 · ReSe2 · Hysteresis · Intrinsic trap states · Photogating |
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