Technology and Applications of Wide Bandgap Semiconductor Materials - Current State and Future Trends

At a Glance

Metadata	Details
Publication Date	2023-09-18
Journal	Energies
Authors	Omar Sarwar Chaudhary, Mouloud Denaï, Shady S. Refaat, Georgios Pissanidis
Institutions	University of Hertfordshire, Texas A&M University at Qatar
Citations	56
Analysis	Full AI Review Included

Technical Documentation: Wide Bandgap Diamond for Power Electronics

This document analyzes the performance and market trends of Wide Bandgap (WBG) semiconductors, focusing specifically on the superior material properties of Diamond (Dia) as detailed in the review paper. It outlines how 6CCVD’s advanced Microwave Plasma Chemical Vapor Deposition (MPCVD) capabilities directly address the current material limitations preventing diamond’s widespread commercial adoption in high-power, high-frequency applications.

Executive Summary

Diamond is the Ultimate WBG Material: Diamond exhibits the highest theoretical performance metrics among all semiconductors, including the widest bandgap (5.47 eV), highest critical electric field ($5.6 \times 10^6$ V/cm), and superior thermal conductivity (20 W/cm·K).
Superior Device Performance: Experimental diamond Schottky Barrier Diodes (SBDs) have already demonstrated extreme performance, achieving breakdown fields up to 9.5 MV/m and blocking voltages exceeding 10 kV, confirming diamond’s potential for ultra-high-voltage power conversion.
Addressing Si Limitations: WBG materials are necessary to overcome the physical limits of Si-based devices, which suffer from high losses, low switching frequencies, and poor performance at high temperatures (limited to 125 °C junction temperature).
Market Opportunity: WBG devices are driving massive efficiency gains and size reductions in critical sectors, including Electric Vehicles (EVs), Data Centers (UPS/PSU), and Industrial Motor Drives (VFDs), promising energy loss reductions of 40% to 85% in various drive cycles.
Material Maturity Gap: The primary barrier to diamond commercialization is the lack of large-area, high-quality, defect-free wafers, with current MWCVD techniques typically limited to 2-inch sizes.
6CCVD Solution: 6CCVD specializes in high-quality MPCVD diamond, offering custom dimensions and doping (BDD) necessary to accelerate the development and commercialization of next-generation diamond power devices.

Technical Specifications

The following table extracts key physical properties comparing Diamond to other major semiconductor materials discussed in the review, highlighting diamond’s inherent advantages for power electronics.

Parameter	Diamond	4H-SiC	GaN	Si	Context
Band gap width ($E_g$)	5.47	3.26	3.39	1.12	Highest energy required for carrier excitation
Critical Electric Field ($E_{crit}$)	$5.6 \times 10^6$	$2.2 \times 10^6$	$3.3 \times 10^6$	$0.25 \times 10^6$	Determines maximum blocking voltage and drift layer thickness
Thermal Conductivity ($\lambda$)	20	7.0	1.5	1.3	W/cm·K (Superior heat dissipation)
Intrinsic Carrier Concentration ($N_i$)	$10^{-20}$	$1.5 \times 10^{-8}$	$2 \times 10^{-10}$	$10^{10}$	cm^-3 (Lowest, resulting in minimal leakage current)
Saturated Electron Drift Velocity ($V_{SAT}$)	$2.7 \times 10^7$	$2.1 \times 10^7$	$2.7 \times 10^7$	$10^7$	cm/s (High speed switching capability)
Demonstrated SBD Breakdown Field	9.5	N/A	N/A	N/A	MV/m (Experimental planar diamond SBD result)
Demonstrated SBD Blocking Voltage	> 10	N/A	N/A	N/A	kV (Experimental planar diamond SBD result)

Key Methodologies

The research paper identifies the following critical material growth and fabrication methodologies necessary for advancing WBG diamond devices:

Epitaxial Growth Techniques: Diamond epitaxial growth is achieved primarily through Chemical Vapor Deposition (CVD), specifically Hot Filament CVD (HF CVD) and Microwave-Enhanced Chemical Vapor Deposition (MWCVD). 6CCVD utilizes advanced MPCVD (a form of MWCVD) to achieve high material quality.
Substrate Limitations: High-Pressure High-Temperature (HPHT) techniques yield high-quality, defect-free diamond but are limited to wafers of only a few millimeters. MWCVD and mosaic-type methods are currently approaching 2-inch wafer sizes.
Heteroepitaxy: Research is ongoing into the heteroepitaxy of diamond on iridium, which has enabled the development of diamond films up to 4 inches, though controlled manufacturing processes are still required.
Doping Control:
- P-type Doping: Easily achieved using Boron, enabling the fabrication of unipolar devices like Schottky Barrier Diodes (SBDs).
- N-type Doping: Remains a significant challenge due to the lack of an efficient charge donor, hindering the development of bipolar and n-channel devices.
Device Architecture: Recent advancements focus on planar diamond power SBDs, which require precise control over doping profiles and metal contacts to achieve high blocking voltage and low switching losses.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-quality, customized diamond materials necessary to overcome the current manufacturing barriers cited in this review and accelerate the commercialization of diamond power electronics.

Applicable Materials

To replicate or extend the high-performance WBG research detailed in this paper, 6CCVD recommends the following materials:

Single Crystal Diamond (SCD): Essential for high-voltage, high-frequency devices (like the SBDs discussed) where defect density must be minimized to achieve maximum critical electric field and low leakage current ($N_i$ of $10^{-20}$ cm^-3). Our SCD offers the highest purity and lowest defect density.
Boron-Doped Diamond (BDD): Crucial for p-type doping, which the paper notes is necessary for fabricating unipolar devices. We supply BDD films and substrates with controlled doping concentrations for optimal device design.
Polycrystalline Diamond (PCD): Ideal for thermal management applications (heat sinks) due to diamond’s superior thermal conductivity (20 W/cm·K), enabling the compact, high-temperature operation required for WBG converters in EVs and data centers.

Customization Potential

6CCVD’s advanced MPCVD and post-processing capabilities directly address the size, quality, and integration challenges facing diamond WBG technology:

Research Requirement / Limitation	6CCVD Capability & Solution	Technical Advantage
Wafer Size Limitation (Current MWCVD limited to 2 inches)	Custom Dimensions: We supply PCD plates/wafers up to 125mm (5 inches), significantly exceeding current commercial limits.	Accelerates large-scale manufacturing and reduces cost per die, addressing a major commercial barrier.
High-Quality Epitaxy (Needed for high $E_{crit}$ and low loss)	SCD Thickness Control: SCD films available from 0.1 µm up to 500 µm, allowing precise control over the critical drift region thickness.	Enables optimization of specific on-resistance ($R_{on,sp}$) and breakdown voltage ($V_B$) trade-offs.
Device Integration (SBDs require metal contacts)	In-House Metalization: Internal capability for depositing Au, Pt, Pd, Ti, W, and Cu contacts.	Provides engineers with reliable, custom metal stacks necessary for ohmic and Schottky contacts in diamond device fabrication.
Surface Finish (Crucial for mobility and low loss)	Ultra-Smooth Polishing: SCD polished to Ra < 1 nm and inch-size PCD polished to Ra < 5 nm.	Minimizes surface scattering, maximizing carrier mobility ($\mu$) and reducing conduction losses in high-frequency FETs.
Thermal Management (Required for high-power modules)	Substrate Thickness: Substrates available up to 10 mm thickness.	Provides robust, high-conductivity heat spreaders for integrated motor drives and high-density power modules.

Engineering Support

6CCVD’s in-house PhD team specializes in MPCVD growth parameters and material characterization. We can assist researchers and engineers with material selection and specification for similar High-Voltage Power Conversion and High-Frequency Switching projects, ensuring the optimal diamond grade (SCD, PCD, or BDD) is chosen to maximize device Figure of Merit (FOM).

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

View Original Abstract

Silicon (Si)-based semiconductor devices have long dominated the power electronics industry and are used in almost every application involving power conversion. Examples of these include metal-oxide-semiconductor field-effect transistors (MOSFETs), insulated-gate bipolar transistors (IGBTs), gate turn-off (GTO), thyristors, and bipolar junction transistor (BJTs). However, for many applications, power device requirements such as higher blocking voltage capability, higher switching frequencies, lower switching losses, higher temperature withstand, higher power density in power converters, and enhanced efficiency and reliability have reached a stage where the present Si-based power devices cannot cope with the growing demand and would usually require large, costly cooling systems and output filters to meet the requirements of the application. Wide bandgap (WBG) power semiconductor materials such as silicon carbide (SiC), gallium nitride (GaN), and diamond (Dia) have recently emerged in the commercial market, with superior material properties that promise substantial performance improvements and are expected to gradually replace the traditional Si-based devices in various power electronics applications. WBG power devices can significantly improve the efficiency of power electronic converters by reducing losses and making power conversion devices smaller in size and weight. The aim of this paper is to highlight the technical and market potential of WBG semiconductors. A detailed short-term and long-term analysis is presented in terms of cost, energy impact, size, and efficiency improvement in various applications, including motor drives, automotive, data centers, aerospace, power systems, distributed energy systems, and consumer electronics. In addition, the paper highlights the benefits of WBG semiconductors in power conversion applications by considering the current and future market trends.

Tech Support

Original Source

DOI: https://doi.org/10.3390/en16186689

References

2014 - A Survey of Wide Bandgap Power Semiconductor Devices [Crossref]
2022 - An overview of lifetime management of power electronic converters [Crossref]
2002 - Silicon carbide benefits and advantages for power electronics circuits and systems [Crossref]
1990 - Potential impact of emerging semiconductor technologies on advanced power electronic systems [Crossref]