Defect Revelation and Evaluation of 4H Silicon Carbide by Optimized Molten KOH Etching Method

Dong, Lin; Zheng, Lianxi; Liu, Xing Fang; Zhang, Feng; Guo, Yan; Li, Xi Guang; Sun, Guangming; Wang, Zhan Guo

doi:10.4028/www.scientific.net/msf.740-742.243

Cited by 12 publications

(6 citation statements)

References 10 publications

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“…Molten-alkali etching is usually adopted to reveal dislocations in 4H-SiC, which removes strained atoms surrounding TDs and forms etch pits at the surface of 4H-SiC. 20,21 Researchers have established an empirical approach to distinguish TSDs from TEDs by assuming that the average size of the etch pits for TSDs is 1.6−2.1 times larger than that of the etch pits for TEDs. 22 and sizes of molten-alkali etched pits significantly vary with the alkali species, etching duration, and doping concentration of 4H-SiC, makes it difficult to discriminate.…”

Section: Introductionmentioning

confidence: 99%

“…Molten-alkali etching is usually adopted to reveal dislocations in 4H-SiC, which removes strained atoms surrounding TDs and forms etch pits at the surface of 4H-SiC. , Researchers have established an empirical approach to distinguish TSDs from TEDs by assuming that the average size of the etch pits for TSDs is 1.6–2.1 times larger than that of the etch pits for TEDs . However, the shapes, densities, and sizes of molten-alkali etched pits significantly vary with the alkali species, etching duration, and doping concentration of 4H-SiC, makes it difficult to discriminate. − More significantly, both synchrotron X-ray-topography (XRT) and transmission-electron-microscopy (TEM) investigations have verified that TMDs are the dominant configurations of TSD/TMDs in 4H-SiC. , However, the morphology of the etch pits of TMDs is still ambiguous, which leads to difficulty in the statistics of the density of TMDs in 4H-SiC.…”

Section: Introductionmentioning

confidence: 99%

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Electronic and Optical Properties of Threading Dislocations in n-Type 4H-SiC

Luo

Yang

et al. 2022

ACS Appl. Electron. Mater.

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Despite the decades of development of the single-crystal growth and homoepitaxy of 4H silicon carbide (4H-SiC), high-density threading dislocations (TDs) still remain in 4H-SiC. In this work, we show that the diameters, depths, and inclination angles of molten-alkali etched pits can be employed to discriminate threading edge dislocations (TEDs), threading screw dislocations (TSDs), and threading mixed dislocations (TMDs) in 4H-SiC. The formation of etch pits of TEDs, TSDs, and TMDs during molten-alkali etching is found to be assisted by the dislocation line, dislocation step, and successively dislocation line and step, respectively. By inspecting the surface potentials of n-type 4H-SiC with Kelvin probe force microscopy (KPFM), we show that both TSDs and TEDs behave as donors in n-type 4H-SiC, which gives rise to charge depletion at TDs in n-type 4H-SiC. TDs are found to participate in the broad band D1 luminescence of 4H-SiC, as evidenced by the fact that the microphotoluminescence (micro-PL) intensities at the centers of TDs are stronger than those in dislocation-free regions of 4H-SiC. Understandings gained in this work may help the optimization of n-type 4H-SiC by manipulating the electronic and optical properties of TDs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electronic and Optical Properties of Threading Dislocations in n-Type 4H-SiC

Luo

Yang

et al. 2022

ACS Appl. Electron. Mater.

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“…Figure 1A displays the OM image of the molten-KOH etched 4H-SiC epitaxial layer. The larger hexagonal pits, the smaller hexagonal pits, and the sea-shell pits correspond to the etch pits of TSDs/TMDs, TEDs, and BPDs, respectively (Konishi et al, 2019;Katsuno et al, 2011;Dong et al, 2013). By the statics of wafer-scale etch-pit density of different dislocations, the average dislocation densities of TSDs/TMDs, TEDs and BPDs are 3,770/cm 2 , 2,352/cm 2 , and 18/cm 2 , respectively.…”

Section: Resultsmentioning

confidence: 97%

Dislocation-related leakage-current paths of 4H silicon carbide

et al. 2023

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Improving the quality of 4H silicon carbide (4H-SiC) epitaxial layers to reduce the leakage current of 4H-SiC based high-power devices is a long-standing issue in the development of 4H-SiC homoepitaxy. In this work, we compare the effect of different type of dislocations, and discriminate the effect of dislocation lines and dislocation-related pits on the leakage current of 4H-SiC by combining molten-KOH etching and the tunneling atomic force microscopy (TUNA) measurements. It is found that both the dislocation lines of threading dislocations (TDs) and the TD-related pits increase the reverse leakage current of 4H-SiC. The dislocation lines of TDs exert more significant effect on the reverse leakage current of 4H-SiC, which gives rise to the nonuniform distribution of reverse leakage current throughout the TD-related pits. Due to the different Burgers vectors of TDs, the effect of TDs on the reverse leakage current of 4H-SiC increases in the order to threading edge dislocation (TED), threading screw dislocation (TSD) and threading mixed dislocation (TMD). Basal plane dislocations (BPDs) are also found to slightly increase the reverse leakage current, with the leakage current mainly concentrated at the core of the BPD. Compared to the effect of TDs, the effect of BPDs on the reverse leakage current of 4H-SiC is negligible. Our work indicates that reducing the density of TDs, especially TMDs and TSDs, is key to improve the quality of 4H-SiC epitaxial layers and reduce the reverse leakage current of 4H-SiC based high -power devices.

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“…The preferential etching processes of TEDs and TSDs proceed along the dislocation lines and dislocation steps, which create hexagonal pits at the surface of molten-KOH etched 4H-SiC. The average size of the etch pits of TSDs is about two times larger than that of TEDs [107,108]. The preferential etching of BPDs in off-axis sliced 4H-SiC starts at the outcrop at the surface, and proceeds along the dislocation line of a BPD, which creates the sea-shell shaped etch pit [109,110].…”

Section: Etch Pits Of Dislocations In 4h-sic Wafersmentioning

confidence: 99%

Dislocations in 4H silicon carbide

Li¹,

Zhang²,

Liu³

et al. 2022

J. Phys. D: Appl. Phys.

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Owning 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 the applications of 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 high density of dislocations is one of the most important bottlenecks for advancing the device 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 wafers and epitaxial layers are introduced. The generation, evolution and annihilation of dislocations during the single-crystals 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 device performance and reliability 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 manipulation of dislocations in 4H-SiC.

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Defect Revelation and Evaluation of 4H Silicon Carbide by Optimized Molten KOH Etching Method

Cited by 12 publications

References 10 publications

Electronic and Optical Properties of Threading Dislocations in n-Type 4H-SiC

Electronic and Optical Properties of Threading Dislocations in n-Type 4H-SiC

Dislocation-related leakage-current paths of 4H silicon carbide

Dislocations in 4H silicon carbide

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