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The state-of-the-art 4H-SiC MOSFETs still suffer from performance (low channel-carrier mobility and high threshold voltage) and reliability (threshold voltage instability) issues. These issues have been attributed to a large density of electrically active defects that exist in the SiO 2 –SiC interfacial region. This paper reviews the earlier and the latest results about the responsible defects for the performance and reliability issues of SiC MOS devices, in the context of the evolution of physical understanding of these defects. The aim of this critical review is to clarify possible confusions due to inconsistencies between the earlier and the latest results. Specific clarifications relate to the physical position of the active defects (whether they are located at or near the SiO 2 –SiC interface) and the energy position of their energy levels (above or below the bottom of conduction band). [ABSTRACT FROM AUTHOR]

Transistor-based on Gallium Nitride (GaN) technology, has enabled energy-saving power electronics to alleviate global energy utilization. Being the initial stages of the development as compared to mature Silicon (Si) technology, the critical issues related to the reliability of GaN-based devices are not much explored. To better understand the device reliability, the article reviews and summarizes, the trapping induced threshold voltage (V T H) instability and dynamic ON-resistance (R D S , O N) degradation specifically, for normally-off p-GaN gate HEMTs in power applications. The variation in threshold voltage and dynamic ON-resistance is examined for different operating regimes, which include biasing voltage and temperature. Furthermore, the characterization methods and test setups are discussed in detail to extract the true value of R D S , O N observed in the GaN power converter. Various models and techniques are reviewed as well which improves the converter conduction losses, introduced by dynamic ON-resistance. Additionally, different techniques are discussed in the review to control the V T H instability. It is observed that the point and extended defects created during device fabrication or charge trapping in GaN buffer, AlGaN layer, surface, or at their interface, induce variation in (V T H) and R D S , O N , for both the gate and drain stress regimes. Threshold voltage stability is mainly affected by the traps below the gate region, while the traps across the gate to drain access region influence the R D S , O N. The variation in R D S , O N value, is seen to be dependent on stress time, different device technology, and, switching conditions (frequency and duty cycle). In power application, the dynamic resistance shows a more pronounced effect on converter efficiency as compared to the V T H. • The article addresses the reliability issues in p-GaN Power HEMTs. • Mainly the trapping-induced V TH instability and R DS, ON degradation are considered. • Various characterization method and test-setup are discussed to extract R DS, ON value. • Methods to control R DS, ON degradation and V TH instability are studied. [ABSTRACT FROM AUTHOR]

This paper reviews the feasibility of the state-of-the-art electrical techniques adopted from Si technology for characterization of SiC MOS devices. The inability of these conventional characterization techniques to correctly evaluate the trap capture cross section and field-effect mobility in SiC MOS devices are investigated and explained. As near-interface traps (NITs) are an important cause of field-effect mobility degradation in SiC MOS devices, which is different from the impact of interface traps in Si devices, these characterization techniques are unable to produce meaningful results. Therefore, special care is required when measuring these NITs in SiC MOS devices. Due to the quantum confinement effect, the NITs located above the conduction band edge are able to capture and release channel electrons from the conduction band via tunnelling. Recent characterization techniques, specifically designed for SiC MOS devices, measure the NITs above the bottom of conduction band and consider the quantum confinement effect to find the energy position of the NITs. These recent characterization techniques are presented in the later part of the paper. [ABSTRACT FROM AUTHOR]