4H silicon carbide (4H‐SiC) holds great promise for high‐power and high‐frequency electronics, in which high‐quality 4H‐SiC wafers with both global and local planarization are cornerstones. Chemical–mechanical polishing (CMP) is the key processing technology in the planarization of 4H‐SiC wafers. Enhancing the performance of CMP is critical to improving the surface quality and reducing the processing cost of 4H‐SiC wafers. In this review, the superior properties of 4H‐SiC and the processing of 4H‐SiC wafers are introduced. The development of CMP with chemical, mechanical, and chemical–mechanical synergistic approaches to improve the performance of CMP is systematically reviewed. The basic principle and processing system of each improvement approach are presented. By comparing the material removal rate of CMP and the surface roughness of CMP‐treated 4H‐SiC wafers, the prospect on the chemical, mechanical, and chemical–mechanical synergistic improvement approaches is finally provided.

Owing to the superior properties of the wide bandgap, high carrier mobility, high thermal conductivity and high stability, 4H silicon carbide (4H-SiC) holds great promise for applications in electrical vehicles, 5G communications, and new-energy systems. Although the industrialization of 150 mm 4H-SiC substrates and epitaxial layers has been successfully achieved, the existence of a high density of dislocations is one of the most severe bottlenecks for advancing the performance and reliability of 4H-SiC based high-power and high-frequency electronics. In this topical review, the classification and basic properties of dislocations in 4H-SiC are introduced. The generation, evolution, and annihilation of dislocations during the single-crystal growth of 4H-SiC boules, the processing of 4H-SiC wafers, as well as the homoepitaxy of 4H-SiC layers are systematically reviewed. The characterization and discrimination of dislocations in 4H-SiC are presented. The effect of dislocations on the electronic and optical properties of 4H-SiC wafers and epitaxial layers, as well as the role of dislocations on the performance and reliability of 4H-SiC based power devices are finally presented. This topical review provides insight into the fundamentals and evolution of dislocations in 4H-SiC, and is expected to provide inspiration for further control of dislocations in 4H-SiC.

The widespread use of 4H silicon carbide (4H-SiC) is just around the corner since high-power electronics based on 4H-SiC are increasingly fabricated to enable the low-carbon development of the world. Quantum technologies are also intensively explored by scrutinizing 4H-SiC as a platform for wafer-scale integration of semiconductor and quantum technologies. Given the importance of impurities and defects for any semiconductor, comprehensive and insightful understanding of impurities and defects in 4H-SiC is imperative. In this Perspective, we summarize recent experimental and theoretical advances in researches on impurities and defects in 4H-SiC after briefly reviewing the history of 4H-SiC. Impurity engineering and defect engineering for the realization of the full potential of 4H-SiC are also discussed. Challenges for the study on impurities and defects in 4H-SiC are finally outlined.

High‐efficiency and low‐loss processing is the mainstay to reduce the cost and deepen the application of 4H silicon carbide (4H‐SiC) wafers in high‐power and high‐frequency electronics. In this study, the high‐yield slicing of 4H‐SiC wafers is realized by combining femtosecond laser irradiation and bandgap‐selective photo‐electrochemical (PEC) exfoliation. By combining light‐absorption measurements, micro‐Raman, and micro‐photoluminescence characterizations, it is found that the damage layer formed inside 4H‐SiC after femtosecond‐laser irradiation consists of amorphous silicon and amorphous carbon. This indicates that the femtosecond‐laser irradiation leads to phase separation in 4H‐SiC. The bandgap of the damage layer is 0.4 eV. Taking advantage of the different bandgap energies of the damage layer and the perfect 4H‐SiC region, the damage layer is removed from the perfect region of 4H‐SiC by using bandgap‐selective PEC etching. During the PEC etching, light‐generated holes can selectively oxidize and corrode the damaged layer with the assistance of the HF solution, and leave the upper and lower perfect 4H‐SiC layers being intact. The current work contributes to the development of the high‐yield and high‐throughput femtosecond laser slicing of 4H‐SiC wafers.

A 23-30-GHz gallium nitride (GaN) low-noise amplifier (LNA) with a noise figure (NF) of 0.87-1.51 dB is presented in this article. This LNA was fabricated with 100-nm gate-length GaN-on-silicon (GaN/Si) microwave monolithic integrated circuit (MMIC) process. The linear gain is 14-17 dB within the band. For investigating the robustness of this LNA, 1-W continuous wave (CW) at 27 GHz was stressed on the input port of the LNA. The gain decreased, and the NF increased after stress. Experimental research and first-principles calculations were carried out to investigate the physical origin of the degradation. The dehydrogenation of V _Ga -H ₃ complexes causes the decrease of gain, and the creation of V _Al -H4in the AlN barrier is supposed to cause an increase of NF.