Electrical Transport of Nb-Doped MoS₂ Homojunction P–N Diode: Investigating NDR and Avalanche Effect
Ehsan Elahi a
a Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic
Proceedings of MATSUS Spring 2026 Conference (MATSUSSpring26)
D4 Synthesis and Integration of 2D Materials for Electronics, Photonics, and Functional Devices
Barcelona, Spain, 2026 March 23rd - 27th
Organizers: Nikolas Antonatos and Filipa M. Oliveira
Poster, Ehsan Elahi, 890
Publication date: 15th December 2025

2D transition metal dichalcogenides (TMDCs) are promising candidates for next generation nanoelectronics and optoelectronics. Yet, controlling layer number, stacking angle, and interfacial quality in van der Waals (vdW) heterostructures remains challenging, often limiting device performance and reproducibility. Homojunctions formed within a single 2D material can circumvent these issues, but their reliable fabrication and systematic exploration of exotic quantum phenomena remain elusive. Here, we report the fabrication and characterization of a thickness-modulated lateral p–n homojunction from a single flake of Nb-doped MoS2. This configuration suppresses interface traps without external interface engineering, enabling excellent and highly stable device performance. The diodes exhibit strong rectifying behavior with a rectification ratio of ≈10⁴ and a remarkably low ideality factor (η = 1.23). Notably, we observe field-dependent negative differential resistance (NDR) at low temperatures, offering unique prospects for unconventional electronic applications. The devices also achieve high photoresponsivity (1.09 × 103 A W−1), external quantum efficiency (2.16 × 10⁵ %), and detectivity (7.5 × 1010 Jones). Furthermore, electrical breakdown studies reveal avalanche multiplication at relatively low voltages, enabling high-performance avalanche photodetectors. Overall, our results demonstrate a simple yet robust approach for probing carrier multiplication in 2D homojunction p–n diodes, underlining the broad potential of TMDCs in advanced optoelectronic and quantum device applications 

The authors acknowledge the assistance provided by the Advanced Multiscale Materials for Key Enabling Technologies project, supported by the Ministry of Education, Youth, and Sports of the Czech Republic. Project No. CZ.02.01.01/00/22_008/0004558, Co-funded by the European Union. Z.S. was supported by ERC-CZ program (project LL2101) from Ministry of Education Youth and Sports (MEYS). G.E. acknowledges support from the Ministry of Education (MOE), Singapore, under AcRF Tier 2 (T2EP50124-0025) and Tier 1 (A-8001995-00-00). P.P.M. was supported by the National Centre for Research and Development, Poland, project No. LIDER/8/0055/L-12/20/NCBR/2021. 

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