Peculiarities of admittance spectroscopy study of wide bandgap semiconductors on the example of diamond
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-01-01 |
| Journal | E3S Web of Conferences |
| Authors | Anna Solomnikova, Vadim Lukashkin, Oleg Derevianko |
| Institutions | Saint Petersburg State Electrotechnical University, Peter the Great St. Petersburg Polytechnic University |
| Citations | 1 |
| Analysis | Full AI Review Included |
Technical Analysis and Documentation: High-Precision Electrical Characterization of Boron-Doped Diamond
Section titled âTechnical Analysis and Documentation: High-Precision Electrical Characterization of Boron-Doped Diamondâ6CCVD Product Focus: Electronic Grade Single Crystal Diamond (SCD) and Custom Boron-Doped Diamond (BDD) Substrates for Power and High-Frequency Electronics.
Executive Summary
Section titled âExecutive SummaryâThis paper successfully utilizes Admittance Spectroscopy (AS) to characterize deep traps (Boron impurities) in semiconductor diamond, a crucial step for advancing high-performance wide bandgap electronics.
- Ultimate Material Confirmation: Diamond demonstrates superior performance metrics, including a Johnson Figure of Merit (JFOM) of 6009 (normalized to Si=1), confirming its potential for power/high-frequency applications.
- Precise Boron Characterization: Achieved highly accurate determination of the Boron activation energy ($E_a$) in heavily-doped diamond at 293 ± 2 meV, with a Mean Squared Error (MSE) below 1%.
- Methodological Rigor: Identified and mitigated key systematic errors in wide bandgap material characterization, specifically addressing issues related to incomplete impurity ionization, low signal/noise ratio, and sample thermal capacity.
- Parameter Optimization: Established optimal experimental conditions, including a minimum thermostating time of 15 minutes and a highly stable temperature ramp rate ($\approx 0.5$ K/min), to ensure high-quality, repeatable conductance spectra.
- Custom Structure Required: The analysis necessitated custom Pt Schottky and Ohmic contacts deposited onto multisectoral HPHT single-crystal diamond plates with varying boron concentrations.
- Relevance to 6CCVD: This research validates the need for precisely doped, high-quality CVD diamond substrates (SCD/BDD) with custom metalization capabilities for scalable electronic device development.
Technical Specifications
Section titled âTechnical SpecificationsâThe following critical data points were extracted from the research concerning material properties and optimized experimental setup.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Baliga Figure of Merit (BFOM) | 474 | Normalized | Comparison relative to Si=1 |
| Johnson Figure of Merit (JFOM) | 6009 | Normalized | Comparison relative to Si=1 |
| Boron Activation Energy ($E_a$) | 293 ± 2 | meV | Calculated from Arrhenius plot (heavily-doped area) |
| Mean Squared Error (MSE) | 2 | meV | High precision result (< 1% error) |
| Optimized Temp. Ramp Rate | 0.5 | K/min | Necessary to eliminate hysteresis in spectra |
| Optimized Thermostating Time | 15 | minutes | Minimum time required for stable G-f spectra |
| Schottky Contact Metal | Platinum (Pt) | N/A | Deposited at 300 °C |
| Schottky Contact Thickness | 100 | nm | Used for both Pt contacts |
| Schottky Contact Diameter | 130 | ”m | Array size for contact array |
| Measurement Frequency Range | 1 kHz - 2 MHz | N/A | Conductance/capacitance spectra range |
| Capacitance Resolution | Up to 1 | fF | Equipment limit for high-sensitivity measurements |
| Optimized Test Signal Amplitude | 80 | meV | Used to increase signal/noise ratio in low-doped samples |
Key Methodologies
Section titled âKey MethodologiesâThe study relied on dynamic admittance spectroscopy applied to HPHT single-crystal diamond plates that were intentionally doped with Boron (B) at varying concentrations (multisectoral structure).
- Material Preparation: Single-crystal diamond plates (HPHT-grown) with multisectoral boron doping (low-doped âwhiteâ areas and heavily-doped âblueâ areas) were used. Boron concentrations differed by at least 10 times.
- Contact Fabrication:
- Upper Side (Schottky): Array of round Platinum (Pt) contacts (130 ”m diameter, 100 nm thick) deposited at 300 °C.
- Bottom Side (Ohmic): Complete coverage with Platinum (Pt, 100 nm thick) deposited at 70 °C.
- Measurement Setup: Admittance measurements utilized an Agilent E4980A RLC-meter, Janis CCR-10 closed-cycle helium probe station, and a LakeShore 336 temperature controller, covering $20 - 450^{\circ} \text{C}$ and 1 kHz - 2 MHz.
- Signal Optimization (Signal/Noise): The test signal amplitude was increased to 80 meV from 30 meV to improve the conductance response quality, especially in low-doped areas where free carrier concentration is minimal.
- Temperature Stabilization (Systematic Error Mitigation):
- Temperature ramp rate was reduced to $\approx 0.5$ K/min to minimize thermal hysteresis.
- Temperature stabilization (thermostating) time was precisely set to 15 minutes before measurement to eliminate systematic errors caused by the thermal capacity of the sample and substrate.
- Data Analysis: Activation energy ($E_a$) was calculated from the temperature conductance spectra using an Arrhenius plot derived from the emission rate equation.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research demonstrates the stringent material and processing requirements for developing advanced diamond electronic devices. 6CCVD is uniquely positioned to supply the customized materials necessary to replicate, scale, and extend this work into manufacturable device prototypes.
| Requirement from Research Paper | 6CCVD Solution & Capability | Customization Potential & Sales Driver |
|---|---|---|
| High-Purity Diamond Base | Electronic Grade SCD (Single Crystal Diamond) | 6CCVDâs MPCVD-grown SCD offers superior crystalline quality and lower native defects compared to HPHT material, essential for stable device performance and higher carrier mobility. |
| Precise Boron Doping | Custom Boron-Doped Diamond (BDD) Films | We offer precise control over Boron incorporation to achieve the specific low-doped and heavily-doped carrier concentrations required for pn-junctions or multisectoral devices. |
| Specific Contact Metalization | Advanced In-House Metalization Services | The paper required Pt contacts deposited at specific temperatures (70 °C and 300 °C). 6CCVD routinely provides custom metal stacks including Au, Pt, Pd, Ti/Pt/Au, and Cu, patterned to client specifications. |
| Microscale Contact Features | Precision Laser Cutting and Patterning | The researchers used 130 ”m contacts. We provide high-fidelity laser structuring and patterning services necessary for creating dense arrays of microcontacts or complex device geometries. |
| Future Scaling Potential | Large-Area PCD/SCD Wafers (Up to 125 mm) | While small samples were used here, 6CCVD can supply inch-size PCD and large SCD plates (up to 125mm PCD) with polishing down to Ra < 5nm, enabling industrial scaling of high-frequency devices. |
| High-Quality Surface Finish | Ultra-Smooth Polishing | Our standard polishing achieves Ra < 1nm on SCD, crucial for minimizing surface traps and interface charge that could interfere with high-accuracy admittance spectroscopy measurements. |
Engineering Support
Section titled âEngineering SupportâThe successful execution of this admittance spectroscopy research relied heavily on meticulous control of experimental parameters to mitigate thermal and electrical noise. 6CCVDâs in-house team of PhD materials scientists and electrical engineers offers consulting services to assist customers in selecting the optimum diamond type, doping profile, and metal stack required for high-frequency Deep Level Transient Spectroscopy (DLTS) and Capacitance-Voltage (C-V) characterization projects.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
To improve the performance characteristics of power and high-frequency electronics, wide bandgap semiconductors are now widely used. This paper presents consideration of features arising during exploration of electronic characteristics of wide bandgap materials. We use the admittance spectroscopy method for analyzing free carrier concentration and boron-impurity activation energy in semiconductor diamond. The special aspect that should be taken into account while studying wide bandgap materials is incomplete ionization of impurity. In this work we adjust the experimental conditions, basing on the previous experience, in particular reduce signal/noise ratio and reckon with heat capacity of the samples and substrate. As a result we obtained high quality conductance spectra and activation energy of boron impurity in low-doped diamond.