A Comprehensive Study on GaN Power Devices: Reliability, Performance, and Application Perspectives

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This review article  (manuscript ID electronics-3903346) by Susmita Mistri and colleagues highlights advances in GaN power semiconductor devices, covering design, packaging, gate-driving strategies, key performance metrics, and market dynamics. It underscores GaN’s transformative role in efficient and durable power solutions.

I suggest the manuscript requires revision to address the highlighted issues before further consideration. 

1. It would be helpful to include a more detailed discussion on the specific challenges and tradeoffs involved in GaN device design, packaging, and integration.

2. The paper highlights the key performance metrics of GaN HEMTs, such as switching speed and thermal management. It could be strengthened by providing a more quantitative comparison of these metrics against traditional silicon-based power devices. This would help readers better understand the relative advantages of GaN technology.

3. The use of reliability assessment techniques like Double Pulse Testing (DPT) is valuable, but it would be valuable to elaborate on the specific methodologies and findings from these reliability studies. I suggest providing deeper insights into the long-term robustness and failure mechanisms of GaN power devices. 
4. The discussion on market dynamics and industry initiatives driving GaN adoption is informative, but it could be strengthened by including more data-driven analysis, such as market size projections, growth rates, and the competitive landscape.

Author Response

1. It would be helpful to include a more detailed discussion on the specific challenges and tradeoffs involved in GaN device design, packaging, and integration.

Response: We appreciate this valuable suggestion. In response, we have enriched Section 2 with an expanded discussion that more clearly articulates the design, packaging, and integration trade-offs of GaN power devices. The revised text now elaborates on the comparative challenges between depletion-mode, cascode, and enhancement-mode HEMTs, emphasizing how gate structure, epitaxial control, and packaging architecture influence switching performance, reliability, and manufacturability. Furthermore, Table 3. has been refined to highlight the impact of packaging types (e.g., QFN, DBC, TO-247) on parasitic inductance, thermal performance, and power density. In addition, Table 4. provides a comparative overview of lateral and vertical GaN loop designs, illustrating their distinct trade-offs in EMI behavior, thermal management, and integration complexity. These revisions collectively strengthen the section by offering a balanced and quantitative perspective on the key challenges and optimization trade-offs in GaN device design and system integration.

2. The paper highlights the key performance metrics of GaN HEMTs, such as switching speed and thermal management. It could be strengthened by providing a more quantitative comparison of these metrics against traditional silicon-based power devices. This would help readers better understand the relative advantages of GaN technology.

Response: We sincerely thank the reviewer for this valuable observation. In the revised manuscript, Section 3. has been enhanced to include a clear quantitative comparison of GaN HEMTs performance against conventional Si and SiC devices. The newly added Table 6. “Comparative Performance Metrics of Silicon, Silicon Carbide, and Gallium Nitride Power Semiconductor Devices (2024-2025 Data),” summarizes key numerical values for switching frequency, on-resistance, thermal resistance, and efficiency. The data demonstrate that GaN devices achieve up to 5 MHz switching frequency, 3-5 times lower on-resistance, and 60-80 % reduction in switching losses compared with silicon devices. These additions provide a precise and data-supported evaluation of GaN’s performance advantages, thereby strengthening the technical depth and clarity of Section 3.

3. The use of reliability assessment techniques like Double Pulse Testing (DPT) is valuable, but it would be valuable to elaborate on the specific methodologies and findings from these reliability studies. I suggest providing deeper insights into the long-term robustness and failure mechanisms of GaN power devices. 

Response: We thank the reviewer for the insightful comment. Following your suggestion, Section 4.2 has been revised to provide a detailed discussion of reliability assessment methodologies and findings. Liu et al. (2025) Double Pulse Testing (DPT) alongside single-pulse tests to systematically investigate degradation and recovery in GaN HEMTs under repetitive surge current stress. Their study revealed a negative shift in threshold voltage (V_th), while R_DS(on) and breakdown voltage (BV) exhibited partial recovery over time, highlighting the complex interplay between degradation and recovery mechanisms. Switching characteristics, including rise/fall times and voltage/current overshoot, were analyzed to identify stress points critical to device reliability. Moreover, Shen et al. (2023) examined electrothermal effects under hard-switching conditions, demonstrating that elevated junction temperatures intensify dynamic on-resistance degradation and reduce long-term device robustness. Collectively, these studies provide deeper insights into the mechanisms governing GaN HEMT reliability, including charge trapping, electrothermal stress, and recovery behavior, thereby supporting the development of strategies to enhance device lifetime in power electronics applications.

 

4. The discussion on market dynamics and industry initiatives driving GaN adoption is informative, but it could be strengthened by including more data-driven analysis, such as market size projections, growth rates, and the competitive landscape.

Response: In response, Section 1. has been revised to provide a more comprehensive, data-driven discussion of market dynamics and industry initiatives promoting GaN adoption. Specifically, Table 2. has been updated to include projected market growth and estimated market value for leading power GaN companies in 2025. The table now presents detailed information on market segments, technology focus, and competitive positioning, providing quantitative insights into growth trends and strategic advantages. These revisions strengthen the section by offering a clearer understanding of the competitive landscape, supporting a more informed perspective on the factors driving GaN adoption in power electronics applications.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript attempts to provide a review of GaN HEMTs in power electronics. While the topic is relevant and of practical interest, the overall quality does not meet the standards of a high-level scholarly review. A good review should critically synthesize the existing literature, highlight the key challenges, compare different approaches, and clearly point out future research directions. Unfortunately, this manuscript falls short in these aspects.

Main issues:

1. The paper mostly lists published results in a descriptive way, without deeper comparison, analysis of conflicting conclusions, or synthesis of broader trends. Several sections simply restate well-known facts without offering new insights or added value.

2. The discussion on critical topics such as device reliability, degradation mechanisms, and application challenges is too brief, with little quantitative data or in-depth commentary.

3. The manuscript includes market forecasts and company descriptions, which make it read more like a technology report than an academic review. Too much space is devoted to industry dynamics and market strategy, while important academic issues (such as detailed comparisons with SiC devices or reliability trade-offs of different GaN architectures) are underdeveloped.

4. The review lacks clear guidance for the field. A strong review should identify open problems, technical bottlenecks, and promising research directions. This manuscript does not provide such perspective for researchers or practitioners.

If the authors wish to pursue publication, the manuscript would need a fundamental restructuring and much deeper critical discussion.

Author Response

1. The paper mostly lists published results in a descriptive way, without deeper comparison, analysis of conflicting conclusions, or synthesis of broader trends. Several sections simply restate well-known facts without offering new insights or added value.

Response: We sincerely thank the reviewer for this valuable feedback. In response, the manuscript has been thoroughly revised to move beyond descriptive reporting and provide a critical, comparative, and trend-focused analysis throughout the review.

• Section 1: The discussion on market dynamics and industry initiatives now incorporates quantitative, data-driven insights, including projected market growth, estimated market values, and strategic positioning of leading power GaN companies. This highlights broader industry trends and adoption drivers in a more analytical manner.
• Section 2: GaN device technologies and design approaches are systematically compared, emphasizing differences in performance, reliability, and application suitability. Conflicting conclusions from prior studies have been critically evaluated, and their implications for device design and selection are clarified.
• Section 3: Reliability and failure mechanisms are synthesized across multiple studies, emphasizing the roles of charge trapping, dynamic on-resistance degradation, electrothermal effects, and recovery behavior. These comparisons provide a deeper understanding of long-term device robustness.
• Section 4: Reliability assessment methodologies, such as Double Pulse Testing and single-pulse analysis, are now discussed with a focus on comparative findings, observed trends, and key stress factors influencing GaN HEMTs performance under practical operating conditions.

These revisions provide a more rigorous, analytical, and insight-driven review, highlighting emerging trends and integrating findings across studies to offer added value beyond previously published results. We believe these changes fully address the reviewer’s concern and significantly strengthen the manuscript.

 

2. The discussion on critical topics such as device reliability, degradation mechanisms, and application challenges is too brief, with little quantitative data or in-depth commentary.

Resposne: In response, Section 3.2 has been thoroughly revised to provide a detailed and quantitative discussion of major reliability issues and challenges in GaN power electronics. Specifically, the revised section now addresses:

• Hot-Carrier Effects and Trap Generation: The mechanisms by which high-energy carriers induce charge trapping, leading to dynamic on-resistance degradation and performance instability, are analyzed with supporting quantitative data.
• Gate Leakage and Dielectric Reliability: Gate leakage phenomena and dielectric breakdown are discussed in the context of device lifetime, including experimental observations and quantitative trends.
• Dynamic R_DS(on) and Current Collapse: The causes, measurement methodologies, and impact on switching performance are elaborated, with reference to both experimental data and comparative studies.
• Threshold Voltage Instability (V_th Shift): Shifts in V_th under stress and their implications for device operation are analyzed in depth.
• Thermal Reliability in Power Modules: The effects of junction temperature, self-heating, and thermal cycling on device degradation and long-term robustness are detailed.
• Kink and Runaway Effects, Inverse Piezoelectric Effect, and Thermomechanical Strain: These phenomena are discussed with respect to their influence on device reliability and failure mechanisms, integrating recent experimental and modeling results.

These revisions provide a more rigorous, in-depth, and quantitative analysis of GaN device reliability, highlighting critical degradation mechanisms and application challenges. By synthesizing findings from recent studies, the section now offers a comprehensive understanding of the factors affecting long-term device performance and robustness, directly addressing the reviewer’s concern.

 

3. The manuscript includes market forecasts and company descriptions, which make it read more like a technology report than an academic review. Too much space is devoted to industry dynamics and market strategy, while important academic issues (such as detailed comparisons with SiC devices or reliability trade-offs of different GaN architectures) are underdeveloped.

Response: We appreciate the reviewer’s feedback. In response, the manuscript has been revised to better balance industry context and academic rigor. While brief market insights are retained, the discussion has been strengthened with detailed technical comparisons between GaN and SiC devices, including performance metrics, reliability trade-offs, and architecture-specific challenges. These revisions focus on academic analysis and synthesis, ensuring the review highlights both emerging trends and critical technical insights, rather than emphasizing market reporting.

• Section 1: Balancing Industrial Context and Academic Rigor

While GaN power technology has achieved notable industrial momentum, the present revision re-orients the discussion toward the scientific and reliability foundations of these devices. Brief references to global market progress are retained only to frame GaN’s technological maturity. The focus of the section now lies in the material physics, design strategies, and reliability phenomena that determine device behavior under practical high-frequency and high-temperature stress. This academic redirection ensures that GaN’s advancement is analyzed through evidence-based performance metrics rather than through industrial or market projections.

 

• Section 2: Comparative Performance Analysis of GaN and SiC Devices

A detailed quantitative comparison between Gallium Nitride (GaN) and Silicon Carbide (SiC) devices has been introduced to clarify their respective advantages across voltage, efficiency, and thermal domains.
GaN HEMTs demonstrate superior switching speed (1-5 MHz versus 0.3-0.8 MHz for SiC), lower on-resistance (3-7 mΩ·cm²), and higher transconductance (15-30 S/mm). These attributes yield rapid transition behavior and reduced switching losses, enabling compact converter architectures suited to 600-650 V systems.
Conversely, this comparison highlights the complementary operating domains of the two materials: GaN demonstrates superior performance in high-frequency, medium-voltage applications requiring high efficiency, whereas SiC maintains a distinct advantage in high-voltage and high-temperature environments. This distinction, derived from intrinsic material properties, establishes a solid technical basis for device selection and system-level optimization in future power electronic designs.

• Section 3: Expansion of Reliability-Focused Analysis

A new, comprehensive reliability subsection has been developed to emphasize degradation physics and architecture-dependent trade-offs, the revisions include:

 

• Detailed analysis of charge-trapping, gate-leakage, hot-carrier effects, and thermal runaway mechanisms (Figures 13-22).
• Comparative reliability evaluation among E-mode, D-mode, cascode, and vertical GaN architectures, highlighting how design structure influences failure modes and dynamic R_DS(on)
• Discussion of reliability qualification procedures (AEC-Q101/102, HTGB, HTRB, and power-cycling tests) and how they validate long-term endurance of GaN power devices.
• Inclusion of recent experimental insights from Double Pulse Testing (DPT) to connect switching stress with degradation pathways in section 4.2

Comparative evaluations among E-mode, D-mode, cascode, and vertical GaN architectures highlight structure-dependent reliability trade-offs. These revisions strengthen the academic value of the review by focusing on physical mechanisms, reliability behavior, and performance optimization rather than market forecasting.

4. The review lacks clear guidance for the field. A strong review should identify open problems, technical bottlenecks, and promising research directions. This manuscript does not provide such perspective for researchers or practitioners.

Response: We sincerely thank the reviewer for this important suggestion. In response, the manuscript has been revised to provide clear guidance for the field. A dedicated discussion now identifies key open problems, critical technical bottlenecks, and promising research directions in GaN power electronics. This includes challenges in reliability, thermal management, device architecture optimization, and system-level integration. By highlighting these gaps and opportunities, the revised manuscript offers actionable insights for both researchers and practitioners, ensuring the review not only synthesizes existing knowledge but also provides a roadmap for advancing the field.

• Section 1: Open Problems in GaN Power Devices

Despite remarkable progress in GaN power technology, several unresolved issues continue to limit its large-scale deployment. Dynamic R_DS(on) instability, charge-trapping effects at the AlGaN/GaN interface, and gate-dielectric degradation remain critical challenges affecting long-term reliability. Furthermore, self-heating and thermal accumulation within high frequency switching operations still constrain performance at elevated power densities. Addressing these problems requires deeper understanding of defect generation, carrier dynamics, and electrothermal coupling in device operation.

• Section 2: Technical Bottlenecks in Device and System Integration

Current GaN device architectures face key bottlenecks in epitaxial uniformity, thermal management, and packaging. The p-GaN gate structure, while enabling normally-off operation, introduces variability in threshold voltage and leakage behavior. In addition, packaging parasitics, EMI noise, and substrate thermal resistance hinder high-speed operation. The monolithic integration of GaN power ICs also presents challenges in isolation, heat spreading, and gate control design, which demand optimization at both material and circuit levels.

• Section 3: Reliability-Focused Research Priorities

Future reliability research should emphasize gate-stack engineering, advanced passivation, and thermal stress mitigation to suppress trap-assisted degradation. Double Pulse Testing (DPT) and accelerated aging evaluations must be used to quantify degradation under repetitive high-voltage and high-temperature stress. Comparative studies among E-mode, D-mode, cascode, and vertical GaN structures are essential to identify architecture-specific failure modes and establish standardized reliability qualification procedures consistent with AEC-Q101/102 criteria.

• Section 4: Promising Research Directions and Outlook

The next generation of GaN research should focus on vertical GaN-on-GaN architectures capable of exceeding 1.2 kV operation with improved thermal conduction, as well as hybrid GaN-SiC solutions combining fast switching with high-voltage robustness. Integration of digital control and real-time health monitoring using machine-learning-based models can further enhance device lifetime prediction and system reliability. Collectively, these directions provide a clear roadmap toward achieving stable, high-efficiency, and sustainable GaN power conversion technologies for future energy systems.

 

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

 Accept in present form

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have revised the manuscript according to the previous comments, and the current version has addressed all major concerns. I recommend the paper for acceptance.