Особенности спектрально-разрешенной термолюминесценции в облученных микрокристаллах нитрида алюминия

At a Glance

Metadata	Details
Publication Date	2020-01-01
Journal	Журнал технической физики
Authors	Д.М. Спиридонов, Д.В. Чайкин, Н.А. Мартемьянов, А.С. Вохминцев, И.А. Вайнштейн
Analysis	Full AI Review Included

Technical Documentation & Analysis: Defect Spectroscopy in Wide Bandgap Materials

Reference Paper: Спиридонов Д.М. et al. (2020). Особенности спектрально-разрешенной термолюминесценции в облученных микрокристаллах нитрида алюминия. Оптика и спектроскопия, 128(9), 1318-1322.

Executive Summary

This research investigates the photoluminescence (PL) and thermoluminescence (TL) properties of non-stoichiometric Aluminum Nitride (AlN) microcrystals, providing critical insights into defect engineering in wide bandgap semiconductors.

Core Achievement: Successful identification and spectroscopic characterization of intrinsic and impurity-related defect centers (vacancies and complexes) in submicron AlN.
Defect Identification: Luminescence is dominated by two bands (3.0 eV and 2.5 eV) attributed to aluminum vacancies (V_Al) and oxygen-vacancy complexes (V_Al-O_N).
Trap Characterization: Nitrogen vacancies (V_N) were confirmed to act as electron traps, exhibiting a thermal activation energy (E_A) of 0.45 eV.
Kinetic Behavior: The TL process follows General Order Kinetics (GOK) with a high kinetic order (b ≈ 2.2), indicating significant charge carrier retrapping.
Application Relevance: The findings are crucial for optimizing AlN performance in applications such as UV LEDs, high-power electronics substrates, and ionizing radiation detectors.
6CCVD Value Proposition: For applications demanding superior thermal management, radiation hardness, and precise defect control (e.g., deep-UV optics, high-power RF), 6CCVD’s MPCVD Single Crystal Diamond (SCD) offers performance metrics vastly exceeding those of AlN.

Technical Specifications

The following hard data points were extracted from the spectroscopic and kinetic analysis of the AlN microcrystals:

Parameter	Value	Unit	Context
Material Stoichiometry	Al:N = 0.9:1	N/A	Cation-deficient AlN
Primary Impurity (Oxygen)	1.6	at.%	O concentration
Secondary Impurity (Silicon)	0.5	at.%	Si concentration
Excitation Wavelength (PL/TL)	260 / 265	nm	UV excitation source
Heating Rate (r)	2	K/s	Constant rate for TL measurements
Dominant PL/TL Peak (II) Energy	3.00 ± 0.05	eV	Associated with V_Al-O_N complexes
Secondary PL/TL Peak (I) Energy	2.50 ± 0.05	eV	Associated with V_Al-2O_N complexes
TL Peak Temperature (T_max)	343 ± 5	K	Main thermoluminescence peak
Activation Energy (E_A)	0.45 ± 0.01	eV	Energy depth of V_N electron traps
Kinetic Order (b)	2.10 - 2.31	N/A	Indicates high retrapping probability (GOK)
SCD Bandgap (Reference)	5.5	eV	6CCVD SCD (Superior wide bandgap material)

Key Methodologies

The experimental procedure focused on controlled synthesis, UV excitation, and high-resolution spectral analysis of the AlN powder:

Synthesis: AlN microcrystalline powder was synthesized using an original gas-phase method involving the simultaneous processing of liquid aluminum with gaseous AlF₃ and NH₃.
Structural Characterization: X-ray phase analysis confirmed a single wurtzite AIN phase (P6₃mc space group) with lattice parameters a = 3.1117 Å and c = 4.9794 Å.
Pre-annealing: Samples were pre-annealed (отжигались) up to 650 K to eliminate prior thermal history.
TL Excitation: Samples were exposed to UV radiation at 260 nm for 3 minutes to populate the charge traps.
TL Measurement: The samples were heated from room temperature up to 650 K at a constant rate of r = 2 K/s. The TL signal was recorded spectrally in the 250-650 nm range with a 10 nm step.
Data Modeling: Experimental PL and TL spectra were analyzed by fitting them to a superposition of two independent Gaussian components (R² > 0.999). Kinetic parameters (E_A, s, b) were determined using the General Order Kinetics (GOK) formalism.

6CCVD Solutions & Capabilities

The research demonstrates the critical importance of defect control and high-performance substrates for advanced optoelectronic and sensing applications. While AlN is a wide bandgap material, diamond offers superior thermal, optical, and mechanical properties, making it the ideal choice for replicating or extending this research into high-power or extreme environment applications.

Applicable Materials for Advanced Wide Bandgap Research

6CCVD provides MPCVD diamond materials tailored to exceed the performance limitations of traditional III-nitrides like AlN:

Application Focus (Based on AlN Paper)	Recommended 6CCVD Material	Key Advantage over AlN
High-Power Electronics Substrates	High Purity PCD or SCD	Thermal conductivity (> 2000 W/mK) is 10x higher than AlN, enabling superior heat dissipation for GaN/AlN HEMT devices. We offer PCD wafers up to 125mm.
UV/Deep-UV Optics & Microlasers	Optical Grade SCD	Excellent transparency and low absorption across the UV spectrum, crucial for high-flux optical components.
Ionizing Radiation Detection/Dosimetry	High Purity SCD or Boron-Doped Diamond (BDD)	Diamond exhibits exceptional radiation hardness and stability. BDD can be tailored for specific conductivity requirements in detector applications (e.g., TL dosimetry).
Advanced Defect Spectroscopy	SCD with Controlled Defect Centers	6CCVD specializes in engineering specific point defects (e.g., NV^-, SiV^-) for quantum sensing, offering precise control over luminescence centers far beyond the intrinsic defects studied in AlN.

Customization Potential for Replication and Extension

To support researchers working on defect engineering, luminescence, and wide bandgap device fabrication, 6CCVD offers comprehensive customization services:

Custom Dimensions: We supply plates and wafers in custom dimensions, including large-area Polycrystalline Diamond (PCD) up to 125mm in diameter, and Single Crystal Diamond (SCD) up to 10mm thick.
Precise Thickness Control: SCD and PCD layers are available from 0.1 µm up to 500 µm, allowing for precise control over active layer volume, critical for TL/PL studies.
Ultra-Smooth Polishing: We achieve surface roughness (Ra) < 1nm for SCD and < 5nm for inch-size PCD, essential for minimizing surface defects that can influence luminescence spectra, as seen in the AlN microcrystals.
Integrated Metalization: For creating electrical contacts required for detector or device testing (e.g., applying bias voltage or measuring conductivity), 6CCVD offers in-house metalization services, including Au, Pt, Pd, Ti, W, and Cu stacks.

Engineering Support

6CCVD’s in-house PhD team provides expert consultation on material selection and defect engineering. We can assist researchers transitioning from AlN or other wide bandgap materials to diamond for projects requiring:

Optimization of defect concentrations (e.g., nitrogen incorporation) to enhance specific luminescence peaks.
Selection of appropriate diamond grades (SCD vs. PCD, BDD vs. intrinsic) based on required thermal, electrical, and optical properties for similar Optoelectronic and Radiation Detection projects.
Guidance on surface preparation and metalization schemes for reliable device integration.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

The regularities of photo- and thermoluminescence processes in submicrosized AlN crystals with cationic deficiency after UV excitation are studied. The observed emission spectra are a superposition of Gaussian bands with maxima at 3.0 and 2.5 eV. The indicated spectral features are due to electronic transitions involving ON impurity and (VAl -ON) oxygen-vacancy complexes. According to a quantitative analysis in the framework of the general order kinetics, carrier capture centers based on VN nitrogen vacancies have an activation energy of 0.45 eV and are responsible for the forming of the thermally stimulated luminescence with maximum at a temperature of 345 K.

Tech Support

Original Source

DOI: https://doi.org/10.21883/os.2020.09.49872.43-20