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

Technical Documentation & Analysis: High-Temperature n-MoS₂/p-DBDD Heterojunction

Executive Summary

This research successfully demonstrates the fabrication and superior high-temperature performance of a heterojunction utilizing heavily Boron-Doped Diamond (DBDD) films, directly validating 6CCVD’s expertise in advanced diamond materials for extreme environments.

Material Validation: Confirms the critical role of p-type heavily Boron-Doped Diamond (DBDD) substrates, synthesized via CVD, in achieving high-quality, thermally stable optoelectronic devices.
Thermal Stability: The n-MoS₂ NSs/p-DBDD heterojunction exhibits stable rectification characteristics across a wide range, from Room Temperature (RT) up to 180 °C.
Record Rectification: Achieved a maximum rectification ratio of $8.11 \times 10^{6}$ at the optimal operating temperature of 100 °C, significantly surpassing performance metrics of lightly doped diamond counterparts.
Degenerate Doping Effect: The high carrier concentration ($5.8 \times 10^{21}$ cm^-3) in the DBDD film facilitates tunneling-dominated current transport, which is essential for the observed electrical behavior.
Advanced Functionality: The device transitions into a Zener diode above 140 °C, confirming its suitability for high-temperature analog circuits, small signal detectors, and memory erasure technology.
Transport Mechanism: Carrier transport is governed primarily by Fowler-Nordheim (F-N) tunneling, making the device highly reliable for operation in harsh, high-temperature environments.

Technical Specifications

The following hard data points were extracted, highlighting the performance and material properties of the n-MoS₂ NSs/p-DBDD heterojunction.

Parameter	Value	Unit	Context
Diamond Material	Heavily Boron-Doped Diamond (DBDD)	N/A	p-type substrate
Carrier Concentration	$5.8 \times 10^{21}$	cm^-3	DBDD film (Hall test)
Resistivity	$1.05 \times 10^{-3}$	$\Omega \cdot$ cm	DBDD film (Hall test)
Mobility	6.8	cm² V^-1 s^-1	DBDD film (Hall test)
Operating Temperature Range	RT to 180	°C	Stable rectification performance
Optimal Rectification Temperature	100	°C	Maximum performance achieved
Maximum Rectification Ratio	$8.11 \times 10^{6}$	N/A	Measured at 100 °C
Reverse Saturation Current	$5.18 \times 10^{-9}$	A	Measured at 100 °C
Ideality Factor (Range)	8.98 - 9.33	N/A	Stable range from RT to 180 °C
Device Active Area	$0.25 \times 0.25$	cm	Heterojunction size
MoS₂ Nanosheet Thickness	98.4	nm	Measured via SEM/AFM
Zener Diode Transition	> 140	°C	Electrical transport behavior change

Key Methodologies

The fabrication process relied on precise CVD growth for the diamond substrate followed by sol-gel deposition for the 2D material.

DBDD Film Preparation (HFCVD):
- Substrate: Silicon wafer.
- CVD Method: Hot-Filament Chemical Vapor Deposition (HFCVD).
- Gases: Flowing H₂ and CH₄.
- Boron Source: Liquid trimethyl borate ((CH₃O)₃B) introduced via H₂ flow, ensuring heavy p-type doping.
- Post-Growth: DBDD film was washed with ethanol and deionized water; retained a hydrogen surface terminal (no irradiation or acid boiling).
MoS₂ Nanosheet Synthesis (Sol-Gel):
- Mo Source: [(NH₄)₆Mo₇O₂₄ $\cdot$ 4H₂O].
- S Source: CH₃CSNH₂.
- Chelating Agent: C₁₄H₂₃N₃O₁₀.
- Sol Preparation: Mixture stirred continuously for one hour, dissolved in 8 mL of deionized water.
Device Assembly and Annealing:
- Deposition: Sol dropped onto the DBDD film center and subjected to spin coating (accelerated from 0 to 3000 rpm within 56 s).
- Curing: Film set on a heating table at 60 °C for 5 min.
- Thickening: Second deposition performed identically.
- Annealing: 400 °C over 4 h to improve bonding quality.
Electrode Fabrication:
- Cathode Contact: Conductive side of transparent Indium Tin Oxide (ITO) glass secured to the MoS₂ NSs surface.
- Anode Contact: p-DBDD film used as the positive electrode.
- Ohmic Contacts: Silver paste and wires used to connect ITO/Ag and BDD/Ag, confirming linear ohmic behavior.

6CCVD Solutions & Capabilities

This research highlights the critical need for high-quality, heavily doped diamond substrates capable of sustaining extreme electrical and thermal loads. 6CCVD is uniquely positioned to supply and enhance the materials required to replicate and scale this high-performance heterojunction technology.

Applicable Materials

The core performance driver in this study is the p-type heavily Boron-Doped Diamond (DBDD) film, which enables the crucial tunneling current mechanism.

Research Requirement	6CCVD Material Solution	Key Benefit
Heavily Boron-Doped Diamond (DBDD)	Heavy Boron-Doped (BDD) MPCVD Diamond	Guaranteed high carrier concentration (up to $10^{21}$ cm^-3 range) necessary for degenerate semiconductor behavior and enhanced tunneling.
High Thermal Conductivity	Electronic Grade PCD or SCD Substrates	Diamond’s intrinsic high thermal conductivity ensures efficient heat dissipation, critical for stable operation up to 180 °C and beyond.
Thin Film/Substrate	SCD/PCD/BDD Films (0.1µm to 500µm)	We offer precise thickness control for both thin films and robust substrates (up to 10mm) to optimize device architecture and thermal management.

Customization Potential for Replication and Scaling

The reported device size ($0.25 \times 0.25$ cm) is small-scale. 6CCVD provides the necessary capabilities to transition this research to commercial, large-area applications:

Large-Area Substrates: We supply Polycrystalline Diamond (PCD) wafers up to 125mm in diameter, enabling high-volume manufacturing of these high-temperature devices.
Custom Dimensions and Cutting: 6CCVD offers precision laser cutting and dicing services to meet exact device dimensions, whether for small research prototypes or large arrays.
Advanced Metalization: While the paper used Ag/ITO contacts, 6CCVD provides in-house metalization services, including Ti/Pt/Au, W, Cu, and Pd, optimized for robust, high-temperature ohmic contacts on BDD surfaces, ensuring long-term device reliability in harsh environments.
Surface Finish: We offer ultra-smooth polishing (Ra < 5nm for inch-size PCD) to ensure optimal interface quality for subsequent 2D material deposition (like MoS₂ NSs), crucial for minimizing barrier inhomogeneity and improving ideality factor.

Engineering Support

The successful development of high-temperature Zener diodes and optoelectronic devices based on the n-MoS₂/p-DBDD heterojunction requires deep material expertise.

Application Focus: 6CCVD’s in-house PhD engineering team specializes in material selection and optimization for high-temperature electronics, memory erasure technology, and extreme environment optoelectronics.
Doping Control: We provide precise control over boron doping levels during MPCVD growth, allowing researchers to fine-tune the Fermi level position and carrier concentration to optimize the tunneling mechanism (F-N vs. direct tunneling) for specific device requirements.
Interface Optimization: We offer consultation on surface termination and polishing techniques to ensure the highest quality interface between the BDD substrate and 2D materials, directly impacting device ideality and rectification performance.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. Global shipping (DDU default, DDP available) ensures rapid delivery of critical materials worldwide.

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]