Photoelectric Performance of Two-Dimensional n-MoS2 Nanosheets/p-Heavily Boron-Doped Diamond Heterojunction at High Temperature

At a Glance

Metadata	Details
Publication Date	2025-05-09
Journal	International Journal of Molecular Sciences
Authors	De-yu Shen, Changxing Li, Dandan Sang, Shunhao Ge, Qinglin Wang
Institutions	Liaocheng University
Analysis	Full AI Review Included

Executive Summary

The research details the fabrication and characterization of a high-performance, thermally stable n-MoS₂ Nanosheets (NSs)/p-Heavily Boron-Doped Diamond (DBDD) heterojunction device.

Superior Thermal Stability: The device maintains typical rectification characteristics across a wide temperature range, from Room Temperature (RT) up to 180 °C, demonstrating excellent thermal stability for harsh environments.
Optimal Performance Point: Maximum rectification ratio (8.11 x 10⁶) and minimum reverse saturation current (5.18 x 10^-9 A) are achieved at 100 °C, identifying this as the optimal operating temperature for forward rectifier diode performance.
Degenerate Doping Advantage: Compared to heterojunctions using lightly B-doped diamond, the DBDD device shows a massive improvement, increasing the rectification ratio by 7.64 x 10⁶ times at 100 °C due to enhanced carrier injection and tunneling.
Zener Diode Transition: The electrical transport mechanism transforms into Zener diode behavior when the temperature exceeds 140 °C, indicating potential for high-temperature voltage regulation.
Transport Mechanism: Carrier transport is dominated by Fowler-Nordheim (F-N) tunneling at high temperatures, driven by Fermi level shifting and the weakening of carrier interband tunneling injection.
Optoelectronic Potential: The device exhibits Photoluminescence (PL) in the yellow-light region (CIE 0.492, 0.505) and Electroluminescence (EL) in the red-light region (CIE 0.309, 0.694).
Fabrication: MoS₂ NSs (96 nm thick) were synthesized via the sol-gel method and deposited onto HFCVD-grown p-DBDD films (carrier concentration 5.8 x 10²¹ cm^-3).

Technical Specifications

Parameter	Value	Unit	Context
Maximum Rectification Ratio	8.11 x 10⁶	Dimensionless	Achieved at 100 °C
Minimum Reverse Saturation Current	5.18 x 10^-9	A	At 100 °C
Zener Diode Transition Temperature	> 140	°C	Electrical transport behavior change
Ideality Factor (n) Range	8.82 - 9.73	Dimensionless	Stable range from RT to 180 °C
DBDD Carrier Concentration	5.8 x 10²¹	cm^-3	p-type heavily doped
DBDD Resistivity	1.05 x 10^-3	Ω cm	Measured via Hall test
DBDD Mobility	6.8	cm² V^-1 s^-1	Measured via Hall test
MoS₂ NS Thickness	96	nm	Measured via AFM
MoS₂ NS Lateral Size	1.1	µm	Average size
PL Emission Coordinates	(0.492, 0.505)	CIE	Yellow-light emission
EL Emission Coordinates	(0.309, 0.694)	CIE	Red-light emission
Conduction Band Offset (∆E_C)	3.8	eV	Anderson Model calculation
Valence Band Offset (∆E_V)	0.37	eV	Anderson Model calculation
Optimal Forward Current (6 V)	0.167	A	At RT

Key Methodologies

The device was constructed by combining a heavily boron-doped diamond (DBDD) substrate with two-dimensional n-MoS₂ nanosheets (NSs).

DBDD Film Preparation (HFCVD):
- DBDD films were grown on a silicon wafer using Hot-Filament Chemical Vapor Deposition (HFCVD).
- The gas mixture included H₂ and CH₄.
- The boron source was liquid trimethyl borate ((CH₃O)₃B), introduced via H₂ flow, with flow rate control used to achieve the heavily doped (degenerate) state.
- The resulting DBDD film was cleaned with ethanol and deionized water.
MoS₂ Nanosheet Synthesis (Sol-Gel Method):
- Precursors: Ammonium heptamolybdate tetrahydrate ([(NH₄)₆Mo₇O₂₄ · 4H₂O]) was used as the Mo source, thioacetamide (CH₃CSNH₂) as the S source, and C₁₄H₂₃N₃O₁₀ as the chelating agent.
- Sol Formation: The mixture was dissolved in 8 mL of deionized water and stirred continuously for one hour.
Heterojunction Fabrication:
- Deposition: The sol was dropped onto the DBDD film and deposited using spin coating, accelerating from 0 to 3000 rpm within 56 s.
- Curing: The coating was cured at 60 °C for 5 minutes.
- Thickening: A second identical deposition was performed.
- Annealing: The bonded device was annealed at 400 °C for 4 hours to improve nanosheet quality.
Electrode Configuration:
- Cathode: Conductive Indium Tin Oxide (ITO) glass was placed in contact with the n-MoS₂ NSs surface.
- Anode: The p-DBDD film served as the positive electrode.
- Contact: Silver paste and wires were used to connect the electrodes, separated by insulating adhesive.

Commercial Applications

This technology leverages the extreme properties of heavily doped diamond combined with 2D materials, making it highly relevant for specialized electronics.

High-Temperature Power Electronics: The exceptional thermal stability (up to 180 °C) and high rectification ratio are ideal for diodes and rectifiers used in high-power switching and conversion systems operating in extreme heat (e.g., industrial furnaces, aerospace systems).
Radiation-Hardened Devices: Diamond’s wide bandgap and chemical stability make the heterojunction suitable for optoelectronic devices and sensors deployed in high-radiation environments (e.g., nuclear facilities, space exploration).
Voltage Regulation and Protection: The observed Zener diode characteristics above 140 °C allow the device to function as a high-temperature voltage regulator or transient voltage suppressor in analog circuits.
Optoelectronic Emitters: The distinct PL (yellow) and EL (red) emission characteristics suggest applications in specialized high-temperature Light Emitting Diodes (LEDs) or integrated optical transmitters.
Non-Volatile Memory Erasure Technology: The strong dependence on Fowler-Nordheim (F-N) tunneling at high temperatures provides a mechanism relevant for developing advanced memory devices and erasure techniques.
High-Frequency/High-Speed Detectors: The combination of high carrier mobility in MoS₂ and the robust diamond interface is beneficial for small signal detectors and high-speed switching applications.

View Original Abstract

Two-dimensional (2D) n-MoS2 nanosheets (NSs) synthesized via the sol-gel method were deposited onto p-type heavily boron-doped diamond (BDD) film to form a n-MoS2/p-degenerated BDD (DBDD) heterojunction device. The PL emission results for the heterojunction suggest strong potential for applications using yellow-light-emitting optoelectronic devices. From room temperature (RT) to 180 °C, the heterojunction exhibits typical rectification characteristics with good results for thermal stability, rectification ratio, forward current decrease, and reverse current increase. Compared with the n-MoS2/p-lightly B-doped (non-degenerate) diamond heterojunction, the heterojunction demonstrates a significant improvement in both its rectification ratio and ideal factor. At 100 °C, the rectification ratio reaches the maximum value and is considered an ideal high temperature for achieving optimal heterojunction performance. When the temperature exceeds 140 °C, the heterojunction transforms into the Zener diode. The heterojunction’s electrical temperature dependence is due to the Fermi level shifting resulting in the weakening of the carrier interband tunneling injection. The n-MoS2 NSs/p-DBDD heterojunction will broaden future research application prospects in the field of high-temperature consumption in future optoelectronic devices.

Tech Support

Original Source

DOI: https://doi.org/10.3390/ijms26104551

References

2022 - Tunable Current Regulative Diode Based on Van der Waals Stacked MoS2/WSe2 Heterojunction-Channel Field-Effect Transistor [Crossref]
2020 - A review of molybdenum disulfide (MoS2) based photodetectors: From ultra-broadband, self-powered to flexible devices [Crossref]
2023 - Research progress of optoelectronic devices based on two-dimensional MoS2 materials [Crossref]
2023 - Two-dimensional MoS2/diamond based heterojunctions for excellent optoelectronic devices: Current situation and new perspectives [Crossref]
2022 - Vertical MoS2 transistors with sub-1-nm gate lengths [Crossref]
2022 - Demonstration of a Sensitive and Stable Chemical Gas Sensor Based on Covalently Functionalized MoS2 [Crossref]
2022 - Hot carriers assisted mixed-dimensional graphene/MoS2/p-GaN light emitting diode [Crossref]
2021 - High-performance MoS2 photodetectors prepared using a patterned gallium nitride substrate [Crossref]
2024 - High-performance flexible photodetectors based on CdTe/MoS2 heterojunction [Crossref]