Microwave loss in low-absorbing diamond-like materials at 1 K < T < 300 K. The phenomenological simulation
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2015-12-21 |
| Journal | RADIOFIZIKA I ELEKTRONIKA |
| Authors | Р. В. Головащенко, V. N. Derkach, S. I. Tarapov |
| Institutions | O.Ya. Usikov Institute for Radiophysics and Electronics, National Academy of Sciences of Ukraine |
| Citations | 2 |
| Analysis | Full AI Review Included |
MICROWAVE LOSS IN DIAMOND-LIKE MATERIALS (1 K < T < 300 K)
Section titled “MICROWAVE LOSS IN DIAMOND-LIKE MATERIALS (1 K < T < 300 K)”Analysis of Phenomenological Modeling for Low-Loss Cryogenic Components
Section titled “Analysis of Phenomenological Modeling for Low-Loss Cryogenic Components”Executive Summary
Section titled “Executive Summary”This documentation analyzes research detailing the phenomenological modeling and experimental measurement of microwave energy loss (Loss Tangent, tgδ) in diamond-like materials, including Polycrystalline CVD-Diamond, Germanium (Ge), Silicon (Si), and Gallium Arsenide (GaAs). The findings are critical for designing ultra-low-loss components used in millimeter-wave and cryogenic microelectronics.
- Application Focus: Study of electromagnetic energy loss mechanisms in materials intended for use in micro- and nanoelectronics operating in the gigahertz (60-120 GHz) range.
- Measurement Method: High-precision measurement of dielectric parameters using Disk Dielectric Resonators (DDR) operating in Whispering Gallery Modes (WGM) across the cryogenic range (1 K to 300 K).
- Loss Mechanisms Identified: Total loss is modeled as the sum of intrinsic (multi-quantum/phonon, Tp dependence) losses and extrinsic (impurity/Debye relaxation) losses.
- Key CVD-Diamond Finding: The minimum loss threshold (tgδ ≈ 1.3 x 10-4) in the tested Polycrystalline CVD-diamond was found to be dominated by extrinsic (impurity/defect) mechanisms, specifically a pronounced Debye relaxation peak near T ≈ 2 K.
- Material Purity Criticality: The analysis confirms that defects and “non-diamond inclusions” significantly expand the range where the Debye relaxation mechanism dominates, preventing the material from achieving its theoretical intrinsic lattice loss limit.
- 6CCVD Value: 6CCVD’s high-purity Single Crystal Diamond (SCD) and quality-controlled Polycrystalline Diamond (PCD) materials are engineered specifically to minimize the non-intrinsic losses identified in this research.
Technical Specifications
Section titled “Technical Specifications”The following table summarizes the key experimental parameters and derived physical constants for the Polycrystalline CVD-diamond sample analyzed in the research.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Frequency Range | 60 - 120 | GHz | Millimeter wave measurement range |
| Temperature Range | 1 - 300 | K | Cryogenic to room temperature test range |
| CVD-Diamond Diameter | 20.06 | mm | Disk Dielectric Resonator (DDR) dimension |
| CVD-Diamond Height (Thickness) | 0.34 | mm | Thin wafer geometry required for WGM |
| Measured Loss Tangent (tgδ) Max | 1.7 x 10-4 | N/A | Peak loss observed near T ≈ 2 K (Extrinsic) |
| Measured Loss Tangent (tgδ) Min | 1.3 x 10-4 | N/A | Lowest measured value for CVD-diamond (T > 2 K) |
| Intrinsic Loss Parameter (A) | 2.771 x 10-5 | N/A | Proportionality coefficient (Eq. 1) |
| Angarmonicity Exponent (p) | 0.319 | N/A | Lattice vibration characteristic |
| Dipole Relaxation Time (τ0) | 2.344 x 10-10 | s | Relaxation constant for Debye mechanism |
| Dipole Activation Energy (W) | 1.669 x 10-4 | eV | Energy required to activate defect relaxation |
| Dipole Concentration Factor (C1) | 6.674 x 10-2 | N/A | Factor dependent on dipole concentration |
Key Methodologies
Section titled “Key Methodologies”The experimental approach focused on precise measurement of dielectric parameters at extreme low temperatures and high frequencies to isolate the competing loss mechanisms.
- High-Precision Measurement Technique: The energetic characteristics of the sample materials were measured using the Disk Dielectric Resonator (DDR) method utilizing Whispering Gallery Modes (WGM). This method ensures that diffraction losses are negligible, making the measured quality factor (Q-factor) highly representative of the material’s intrinsic losses (tgδ ≈ 1/2Q).
- Sample Preparation: Resonators were fabricated from the test materials (including CVD-diamond) into high-optical precision discs, with dimensions selected to support WGM resonances (Diameter ≈ several wavelengths, Height ≈ half-wavelength). Surfaces were meticulously cleaned prior to measurement.
- Experimental Setup: Measurements were conducted using a Cryodielectrometer (part of the Cryomagnetic Radiospectroscopy Complex) capable of controlling temperatures from 1 K up to 300 K.
- Phenomenological Modeling: Experimental data was fitted using a combined model (Equation 3) that sums the two primary loss components:
- Intrinsic Loss (tgδph): Dominated by the multi-quantum/phonon mechanism (Tp dependence).
- Extrinsic Loss (tgδdb): Dominated by the Debye dipole relaxation mechanism, caused by impurities/defects (dipoles) in the lattice.
- Data Fitting Algorithm: The Levenberg-Marquardt algorithm was utilized for iterative non-linear curve fitting to determine the physical parameters (A, p, τ0, W, C1) that characterize the material loss behavior.
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”The research highlights that achieving ultra-low microwave loss, particularly at cryogenic temperatures, hinges entirely on minimizing extrinsic losses caused by defects and inclusions (Debye mechanism). 6CCVD’s MPCVD expertise delivers the ultra-high purity materials necessary to replicate and advance this research by suppressing the impurity-driven loss peak observed at 2 K.
| Research Requirement or Finding | 6CCVD Material/Capability | Engineering Value Proposition |
|---|---|---|
| Material Needed: Low-absorbing, diamond-like material with minimal defects/impurities. | Optical Grade Single Crystal Diamond (SCD): Epitaxial growth yielding ultra-high purity material (N/B controlled to ppb level). | SCD guarantees the lowest theoretical intrinsic loss floor (lattice anharmonicity), effectively eliminating the high-loss extrinsic Debye peak observed near 2 K in the lower-purity CVD-Almaz sample. |
| Material Needed: Scalable large-area dielectric windows for millimeter-wave systems (e.g., Gyrotrons). | High Purity Polycrystalline Diamond (PCD): Custom wafers up to 125mm in diameter. | Provides large-area, high-thermal-conductivity windows required for high-power microwave components, with superior impurity control compared to the standard CVD-Almaz analyzed. |
| Dimension Requirement: Highly specific, thin disc geometry (20.06 mm D, 0.34 mm H) requiring optical precision. | Custom Dimensions & Processing: Plates/wafers available up to 125mm. We provide precise wafer processing, laser cutting, and dicing to meet exact DDR specifications (including thickness tolerances from 0.1 µm up to 500 µm). | Enables direct replication and extension of WGM/DDR experiments with complex geometries, ensuring stable resonance characteristics. |
| Surface Requirement: Ultra-smooth, optical-grade surfaces essential for minimal scattering and high Q-factors. | Precision Polishing: Single Crystal Diamond (SCD) with Ra < 1nm. Inch-size Polycrystalline Diamond (PCD) with Ra < 5nm. | Minimizes surface scattering losses which become increasingly significant at 60-120 GHz frequencies, ensuring the measured loss tangent truly reflects bulk material properties. |
| Future Needs: Integration of metal electrodes or conductive layers for active components (similar to the Si:Au samples studied). | Custom Metalization: Internal capability to deposit Au, Pt, Pd, Ti, W, and Cu metal stacks. | Provides turnkey integration of diamond wafers into complex devices (e.g., semiconductor substrates or sensors) without requiring external processing steps. |
| Design Requirement: Assistance with material selection and purity specification for cryogenic/microwave projects. | Engineering Support: Our in-house PhD material science team assists clients in correlating required physical parameters (like activation energy W or concentration C1) with specific material growth recipes. | Accelerates R&D cycles by matching performance requirements for complex millimeter-wave and cryogenic diamond applications. |
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
The development and manufacture of new materials for micro- and nanoelectronics are inextricably linked with the problem of studying the electromagnetic energy loss mechanisms in these materials in the gigahertz band. The reasonable technique of search for these mechanisms is the analysis of the temperature dependence of the loss tangent of such materials at temperatures from cryogenic ones to room ones. In this paper, the phenomenological simulation of loss in low-absorbing materials having a diamond-like crystal lattice is performed on the basis of experimental data. The experiments were carried out in the frequency range 60…120 GHz and at temperatures 1…300 K. The technique of measuring energy characteristics of the whispering gallery mode disk dielectric resonator is applied. As a result, the roles of main loss mechanisms for the materials under research are clarified and the values of basic physical parameters of materials are determined.