Negative Differential Resistance of n-ZnO Nanorods/p-degenerated Diamond Heterojunction at High Temperatures
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-07-15 |
| Journal | Frontiers in Chemistry |
| Authors | Dandan Sang, Jiaoli Liu, Xiaofeng Wang, Dong Zhang, Feng Ke |
| Institutions | Stanford University, Liaocheng University |
| Citations | 18 |
| Analysis | Full AI Review Included |
Technical Analysis and Documentation: High-Temperature Diamond Heterojunctions
Section titled âTechnical Analysis and Documentation: High-Temperature Diamond HeterojunctionsâExecutive Summary
Section titled âExecutive SummaryâThis documentation analyzes the successful fabrication and characterization of an n-ZnO Nanorods/p-degenerated Diamond heterojunction, demonstrating robust Negative Differential Resistance (NDR) at elevated temperatures.
- Core Achievement: Successful realization of a tunneling diode utilizing heavily Boron-Doped Diamond (BDD) that exhibits NDR phenomena up to 80 °C.
- Material Performance: The p-degenerated diamond exhibited a high carrier concentration (1.7 x 1020 cm-3), confirming its suitability for high-power, high-temperature electronics.
- Device Metrics: A Peak-to-Valley Current Ratio (PVCR) of 1.7 was achieved at 20 °C, decreasing slightly to 1.1 at 80 °C.
- High-Temperature Operation: Operating at 80 °C resulted in a significant increase in forward current (up to 10 times higher than 20 °C) and a reduced turn-on voltage (from 1.5 V to 0.7 V).
- Mechanism Validation: The study confirms that carrier transport is dominated by band-to-band tunneling and Fowler-Nordheim (FN) tunneling in the high-bias region.
- Application Potential: These findings provide essential insight for designing and optimizing new-type NDR devices, resistive switching components, and resonant tunneling diodes for harsh, high-temperature environments.
Technical Specifications
Section titled âTechnical SpecificationsâThe following table summarizes the key material properties and electrical performance metrics extracted from the research.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Material Type | p-degenerated | N/A | Heavily Boron-Doped Diamond (BDD) |
| BDD Carrier Concentration | 1.7 x 1020 | cm-3 | Essential for degenerated semiconductor structure |
| BDD Film Thickness | 4 | ”m | Synthesized by HFCVD |
| BDD Resistivity | 102 | Ω cm | Measured by Hall effect |
| ZnO Nanorod Diameter | ~80 | nm | Average dimension |
| ZnO Nanorod Length | ~2 | ”m | Average dimension |
| Peak Current (Ip) (80 °C) | 20.4 | ”A | High-temperature performance |
| Valley Current (Iv) (80 °C) | 19.3 | ”A | High-temperature performance |
| PVCR (20 °C) | 1.7 | N/A | Maximum observed ratio |
| PVCR (80 °C) | 1.1 | N/A | Performance at elevated temperature |
| Turn-on Voltage (80 °C) | 0.7 | V | Minimum observed voltage |
| Maximum Tested Temperature | 120 | °C | NDR effect disappeared above 80 °C |
Key Methodologies
Section titled âKey MethodologiesâThe device fabrication relied on precise CVD techniques for diamond growth and subsequent thermal processing for nanorod synthesis.
- Substrate Preparation: Silicon wafers (1 cm x 1 cm) were mechanically abraded using diamond paste to enhance nucleation density, followed by ultrasonic cleaning.
- Diamond Synthesis (HFCVD): P-degenerated diamond film was grown using a 150 V bias-assisted Hot Filament Chemical Vapor Deposition (HFCVD) method.
- HFCVD Recipe Parameters:
- Filament Heating: Spiral Tantalum wire heated to ~2,000 °C.
- Substrate Temperature: ~700-800 °C.
- Total Pressure: 40 Torr.
- Gas Flow Rate (CH4/H2): 2.6 / 200 sccm.
- Boron Source: Liquid B(OCH3)3 incorporated via 20 sccm H2 bubbling.
- ZnO Nanorod (NR) Fabrication: ZnO NRs were synthesized on the BDD film via thermal evaporation in a horizontal tube furnace.
- Thermal Evaporation Parameters:
- Source Material: Mixed ZnO and Aluminum powders heated to 850 °C.
- Substrate Temperature: ~500 °C (BDD substrate placed downstream).
- Constant Pressure: 6 x 104 Pa.
- Device Contacting: A transparent conductive Indium-Tin-Oxide (ITO) glass was used as the negative electrode (on ZnO NRs), and a Silver (Ag) wire was used as the positive electrode (on BDD).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is uniquely positioned to supply the high-quality, heavily doped diamond materials and custom fabrication services required to replicate, optimize, and scale this high-temperature NDR technology.
| Research Requirement | 6CCVD Solution & Capability | Technical Advantage |
|---|---|---|
| Material: Heavily Boron-Doped Diamond (BDD) | Heavy Boron-Doped Polycrystalline Diamond (PCD-BDD): We specialize in MPCVD BDD with precise, uniform doping control, achieving concentrations exceeding 1021 cm-3. | Guarantees the highly conductive, degenerated semiconductor behavior (p-degenerated structure) essential for quantum tunneling and high-power device stability. |
| Dimensions & Scaling: 1 cm x 1 cm substrates | Custom Dimensions up to 125 mm: We provide PCD plates and wafers up to 125 mm (5 inches) in diameter. | Facilitates immediate scaling from R&D prototypes to commercial, large-area device fabrication for high-volume manufacturing. |
| Thickness Control: 4 ”m diamond film | Precise Thickness Control: SCD and PCD layers available from 0.1 ”m up to 500 ”m, with substrates up to 10 mm thick. | Allows for exact replication of the 4 ”m layer or optimization of junction thickness for specific electrical characteristics (e.g., capacitance, breakdown voltage). |
| Surface Quality: Smooth surface required for heterojunction growth | Ultra-Low Roughness Polishing: Polycrystalline diamond (PCD) polishing to Ra < 5 nm (inch-size). Single Crystal Diamond (SCD) polishing to Ra < 1 nm. | Minimizes interfacial defects and roughness at the ZnO/Diamond interface, which is critical for maximizing carrier tunneling efficiency and PVCR. |
| Device Contacts: Ag and ITO electrodes | Custom Metalization Services: Internal capability for depositing Au, Pt, Pd, Ti, W, and Cu layers. | Provides flexibility for integrating robust ohmic contacts and complex electrode structures necessary for reliable operation in high-temperature and high-power environments. |
| Engineering Support: High-Temperature NDR/Tunneling Applications | In-House PhD Engineering Team: Dedicated support for material selection, doping profile design, and surface preparation for wide-bandgap heterojunctions. | Accelerates R&D cycles by ensuring optimal diamond material properties (thermal conductivity, stability, and doping) are met for harsh environment electronics. |
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
In the present study, an n-ZnO nanorods (NRs)/p-degenerated diamond tunneling diode was investigated with regards to its temperature-dependent negative differential resistance (NDR) properties and carrier tunneling injection behaviors. The fabricated heterojunction demonstrated NDR phenomena at 20 and 80°C. However, these effects disappeared followed by the occurrence of rectification characteristics at 120°C. At higher temperatures, the forward current was increased, and the turn-on voltage and peak-to-valley current ratio (PVCR) were reduced. In addition, the underlying mechanisms of carrier tunneling conduction at different temperature and bias voltages were analyzed through schematic energy band diagrams and semiconductor theoretical models. High-temperature NDR properties of the n-ZnO NRs/p-degenerated diamond heterojunction can extend the applications of resistive switching and resonant tunneling diodes, especially in high-temperature, and high-power environments.
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
Section titled âReferencesâ- 2018 - Facile fabrication of self-assembled ZnO nanowire network channels and its gatecontrolled UV detection [Crossref]
- 2011 - Resistive switching characteristics of maghemite nanoparticle assembly. J [Crossref]
- 2007 - Room temperature observation of negative differential resistance effect using ZnO nanocrystal structure with double Schottky barriers [Crossref]
- 2015 - Observation of room temperature negative differential resistance in solution synthesized ZnO nanorod [Crossref]
- 2007 - Physics of Semiconductor Devices
- 2017 - High-sensitive Ultraviolet photodetectors based on ZnO Nanorods/CdS heterostructures [Crossref]
- 2006 - Boron spectral density and disorder broadening in B-doped diamond [Crossref]
- 2013 - Epitaxial growth of ZnO nanorods on diamond and negative differential resistance of n-ZnO nanorod/p-diamond heterojunction [Crossref]
- 2010 - Investigation on crystalline structure, boron distribution, and residual stresses in freestanding boron-doped CVD diamond films [Crossref]
- 2018 - Temperature dependent negative differential resistance behavior in multiferroic metal organic framework (CH3)2NH2Mn(HCOO)3 crystals [Crossref]