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6CCVD Research

Photoluminescence and Electrical Properties of n-Ce-Doped ZnO Nanoleaf/p-Diamond Heterojunction

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2022-10-26
JournalNanomaterials
AuthorsQinglin Wang, Yu Yao, Xianhe Sang, Liangrui Zou, Shunhao Ge
InstitutionsLudong University, Liaocheng University
Citations8
AnalysisFull AI Review Included

Executive Summary

Section titled “Executive Summary”

This study successfully fabricated and characterized an n-Ce:ZnO Nanoleaf (NL)/p-Boron-Doped Diamond (BDD) heterojunction, demonstrating superior performance compared to undoped counterparts, particularly in high-temperature environments.

  • Enhanced Optoelectronics: Ce doping significantly improved photoluminescence (PL) intensity and induced a pronounced blue shift in the UV emission peak (from 385 nm to 365 nm), shifting the device’s chromaticity coordinates toward the dark blue region.
  • High Thermal Stability: The heterojunction exhibits excellent rectification characteristics and stable electrical performance up to 175 °C, making it suitable for harsh environment applications.
  • Improved Rectification: The rectification ratio at ±8 V dramatically increased from 1.38 (25 °C) to 29.37 (175 °C), indicating superior high-temperature diode behavior.
  • Reduced Operating Voltage: The turn-on voltage (Von) decreased with temperature, dropping from 0.6 V (25 °C) to 0.4 V (175 °C).
  • Carrier Transport Mechanism: At high temperatures, the dominant carrier transport mechanism shifts from band-to-band tunneling (at room temperature) to thermionic emission, confirming the viability of the device structure for high-temperature operation.
  • Material Structure: Ce:ZnO NLs were grown via a hydrothermal method, maintaining a hexagonal wurtzite structure, with nanoleaves averaging 1.6 ”m in length and 7.9 nm in thickness.

Technical Specifications

Section titled “Technical Specifications”
ParameterValueUnitContext
BDD Band Gap5.47eVIntrinsic property
BDD Electron-Hole Mobility2400cm2/(V · s)Intrinsic property
BDD Carrier Concentration1.46 x 1018cm-3Measured via Hall effect
BDD Resistivity1.09 x 10-1Ω cmMeasured via Hall effect
Ce:ZnO NL Length1.6”mAverage dimension
Ce:ZnO NL Thickness7.9nmAverage dimension
Ce Content (wt%)0.20wt%EDS analysis of Ce:ZnO NLs
UV Emission Peak (Doped)365nmn-Ce:ZnO NL/p-BDD (Blue Shifted)
UV Emission Peak (Undoped)385nmn-ZnO/p-BDD
Turn-on Voltage (175 °C)0.4Vn-Ce:ZnO NL/p-BDD heterojunction
Turn-on Voltage (25 °C)0.6Vn-Ce:ZnO NL/p-BDD heterojunction
Rectification Ratio (175 °C)29.37Ratio (at ±8 V)Significant high-temperature performance
Rectification Ratio (25 °C)1.38Ratio (at ±8 V)Room temperature performance
Ideal Factor (n) (175 °C)4.61DimensionlessDecreases with temperature
Ideal Factor (n) (25 °C)6.72DimensionlessHigh value indicates tunneling/defects
Injection Efficiency (a) (175 °C)0.57V-1Moderate forward voltage (Region II)

Key Methodologies

Section titled “Key Methodologies”

The fabrication involved two main steps: BDD film preparation and Ce:ZnO Nanoleaf growth via a hydrothermal method.

  1. p-BDD Film Preparation:

    • Method: Hot Filament Chemical Vapor Deposition (HFVVD).
    • Thickness: Approximately 4 ”m.

  2. ZnO Seed Layer Deposition:

    • Method: Magnetron sputtering onto the BDD films.
    • Thickness: Approximately 20 nm.

  3. n-Ce:ZnO NL Hydrothermal Synthesis:

    • Precursor Solution Components:
      • Zinc acetate dihydrate (Zn(CH3COO)2 · 2H2O): 0.2 M
      • Cerium nitrate hexahydrate (Ce(NO3)2 · 6H2O): 11 mM
      • Hexamethylenetetramine (CH2)6N4): 3 mM
      • Anhydrous ethanol.
    • pH Adjustment: NaOH was added until the precursor solution reached pH 10.
    • Growth Conditions: The solution was transferred to an autoclave and treated at 150 °C for 24 hours.
    • Post-Processing: Rinsed repeatedly with absolute ethanol for 5 minutes and dried at room temperature (RT).

  4. Characterization Techniques:

    • Morphology: Scanning Electron Microscopy (SEM).
    • Elemental Composition: Energy-Dispersive X-ray Spectroscopy (EDS) and X-ray Photoelectron Spectroscopy (XPS).
    • Crystalline Structure: X-ray Diffractometry (XRD) (Cu Kα radiation).
    • Optical Properties: Photoluminescence (PL) spectroscopy (325 nm excitation).
    • Electrical Performance: Keithley 2400 source meter for Current-Voltage (I-V) measurements (25 °C, 100 °C, 175 °C).

Commercial Applications

Section titled “Commercial Applications”

The n-Ce:ZnO NL/p-BDD heterojunction, leveraging the chemical stability and high thermal conductivity of diamond combined with the tunable optical properties of Ce-doped ZnO, is highly valuable for specialized optoelectronic devices operating under extreme conditions.

  • Harsh Environment Optoelectronics:
    • High-temperature sensors and detectors (e.g., automotive, aerospace, industrial monitoring).
    • Radiation-resistant devices (due to BDD’s inherent radiation hardness).
  • High-Power Electronics:
    • Rectifiers and diodes requiring stable operation at elevated temperatures (up to 175 °C and potentially higher).
  • UV Light-Emitting Devices (LEDs):
    • Fabrication of dark blue region LEDs, utilizing the enhanced and blue-shifted UV emission achieved through Ce doping.
  • Chemical and Gas Sensing:
    • BDD/ZnO nanostructures are known for sensing applications; the high surface area of the NL morphology and the defect control via Ce doping could enhance sensitivity and stability.
View Original Abstract

The n-type Ce:ZnO (NL) grown using a hydrothermal method was deposited on a p-type boron-doped nanoleaf diamond (BDD) film to fabricate an n-Ce:ZnO NL/p-BDD heterojunction. It shows a significant enhancement in photoluminescence (PL) intensity and a more pronounced blue shift of the UV emission peak (from 385 nm to 365 nm) compared with the undoped heterojunction (n-ZnO/p-BDD). The prepared heterojunction devices demonstrate good thermal stability and excellent rectification characteristics at different temperatures. As the temperature increases, the turn-on voltage and ideal factor (n) of the device gradually decrease. The electronic transport behaviors depending on temperature of the heterojunction at different bias voltages are discussed using an equilibrium band diagram and semiconductor theoretical model.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2006 - Quasi-one-dimensional metal oxide materials—Synthesis, properties and applications [Crossref]
  2. 2018 - Structural, optical and electrical properties of a Schottky diode fabricated on Ce doped ZnO nanorods grown using a two step chemical bath deposition [Crossref]
  3. 2002 - Nanowire Ultraviolet Photodetectors and Optical Switches [Crossref]
  4. 1994 - ZnO-thin film chemical sensors
  5. 1994 - Growth of ZnO films on GaAs substrates with a SiO2 buffer layer by RF planar magnetron sputtering for surface acoustic wave applications [Crossref]
  6. 2021 - High performance NiO/Ag/NiO transparent conducting electrodes for p-Si/n-ZnO heterojunction photodiodes [Crossref]
  7. 2015 - n-ZnO/p-4H-SiC diode: Structural, electrical, and photoresponse characteristics [Crossref]
  8. 2020 - Enhanced Piezoresistive Behavior of SiC Nanowire by Coupling with Piezoelectric Effect [Crossref]
  9. 2021 - Preparation and photoelectrochemical properties of hierarchical heterostructure ZnO/CuO array [Crossref]

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