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

Gao, Wandong; Yang, Guang; Qian, Yixiao; Han, Xuefeng; Cui, Can; Pi, Xiaodong; Yang, Deren; Wang, Rong

doi:10.3389/fmats.2023.1022878

Cited by 8 publications

(4 citation statements)

References 42 publications

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“…Despite the great success of 4H-SiC in electrical vehicles and photovoltaic converters, the potential of 4H-SiC in ultra-high-power electronics has not been fully addressed due to the high density of dislocations that deteriorate the device performance and exert reliability issues [4−6] . For example, dislocations have been found to increase the leakage current of 4H-SiC-based high-power devices [7,8] . Although most of basal plane dislocations (BPDs) in 4H-SiC substrates are converted to threading edge dislocations (TEDs) during homoepitaxy, the residual BPDs in homoepitaxial 4H-SiC still trigger bipolar degradation of 4H-SiC-based bipolar devices [9,10] .…”

Section: Introductionmentioning

confidence: 99%

Anisotropic etching mechanisms of 4H-SiC: Experimental and first-principles insights

Yang,

Xu,

Cui

et al. 2024

J. Semicond.

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Molten-alkali etching has been widely used to reveal dislocations in 4H silicon carbide (4H-SiC), which has promoted the identification and statistics of dislocation density in 4H-SiC single crystals. However, the etching mechanism of 4H-SiC is limited misunderstood. In this letter, we reveal the anisotropic etching mechanism of the Si face and C face of 4H-SiC by combining molten-KOH etching, X-ray photoelectron spectroscopy (XPS) and first-principles investigations. The activation energies for the molten-KOH etching of the C face and Si face of 4H-SiC are calculated to be 25.09 and 35.75 kcal/mol, respectively. The molten-KOH etching rate of the C face is higher than the Si face. Combining XPS analysis and first-principles calculations, we find that the molten-KOH etching of 4H-SiC is proceeded by the cycling of the oxidation of 4H-SiC by the dissolved oxygen and the removal of oxides by molten KOH. The faster etching rate of the C face is caused by the fact that the oxides on the C face are unstable, and easier to be removed with molten alkali, rather than the C face being easier to be oxidized.

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Section: Introductionmentioning

confidence: 99%

Anisotropic etching mechanisms of 4H-SiC: Experimental and first-principles insights

Yang,

Xu,

Cui

et al. 2024

J. Semicond.

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“…The origins of these defects are often related to many factors, such as substrate quality, growth temperature and cavity structure, and the crystal structure of these defects is usually complicated [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. High-voltage and high-power SiC power electronic devices need a large active area to realize high-current applications [ 16 , 17 , 18 , 19 , 20 ]. Defects in the active region degrade the performance of devices and further lead to device failure.…”

Section: Introductionmentioning

confidence: 99%

Influence of Growth Process on Suppression of Surface Morphological Defects in 4H-SiC Homoepitaxial Layers

Pei,

Yuan,

et al. 2024

Micromachines

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To address surface morphological defects that have a destructive effect on the epitaxial wafer from the aspect of 4H-SiC epitaxial growth, this study thoroughly examined many key factors that affect the density of defects in 4H-SiC epitaxial wafer, including the ratio of carbon to silicon, growth time, application of a buffer layer, hydrogen etching and other process parameters. Through systematic experimental verification and data analysis, it was verified that when the carbon–silicon ratio was accurately controlled at 0.72, the density of defects in the epitaxial wafer was the lowest, and its surface flatness showed the best state. In addition, it was found that the growth of the buffer layer under specific conditions could effectively reduce defects, especially surface morphology defects. This provides a new idea and method for improving the surface quality of epitaxial wafers. At the same time, we also studied the influence of hydrogen etching on the quality of epitaxial wafers. The experimental results show that proper hydrogen etching can optimize surface quality, but excessive etching may lead to the exposure of substrate defects. Therefore, it is necessary to carefully control the conditions of hydrogen etching in practical applications to avoid adverse effects. These findings have important guiding significance for optimizing the quality of epitaxial wafers.

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“…In situ measurements of temperature, flow velocity, species distribution, and growth rate inside the growth chamber are extremely difficult although X-rays have been used in the past to observe the evolution of source powder and crystals during growth. [10] This explains why the PTV method still faces many difficulties in terms of diameter expansion and defect reduction [11][12][13] since the defects are directly related to the transport phenomena in the crystal growth process. Numerical simulation has therefore developed rapidly in recent years as a powerful tool to study the multi-physics phenomena in a single-crystal SiC growth system.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of the Transport of Gas Species in the PVT Growth of Single‐Crystal SiC

Xu,

Han,

et al. 2024

Cryst. Res. Technol.

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Single‐crystal silicon carbide (SiC) is an important semiconductor material for the fabrication of power and radio frequency (RF) devices. The major technique for growing single‐crystal SiC is the so‐called physical vapor transport (PVT) method, in which not only the thermal field but also the fluid‐flow field and the distribution of gas species can be hardly measured directly. In this study, a multi‐component flow model is proposed that includes the inside and outside of a growth chamber and a joint between the seed crystal holder and crucible which allows exchanges of the gas species. The joint is simulated as a thin porous graphite sheet. The Hertz‐Knudsen equation is used to describe the sublimation and deposition. The convection and diffusion are described by the Navier–Stokes equations and mixture‐averaged diffusion model, in which the Stefan flow is taken into account. The numerical simulations are conducted by the finite element method (FEM) with a multi‐physics coupled model, which is able to predict the fluid flow field, species distribution field, crystal growth rate, and evolution of the molar concentration of dopant gas. Using this model, the effects of several experimental conditions on the transport of gas species and the growth rate of single‐crystal SiC are analyzed.

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

Cited by 8 publications

References 42 publications

Anisotropic etching mechanisms of 4H-SiC: Experimental and first-principles insights

Anisotropic etching mechanisms of 4H-SiC: Experimental and first-principles insights

Influence of Growth Process on Suppression of Surface Morphological Defects in 4H-SiC Homoepitaxial Layers

Numerical Simulation of the Transport of Gas Species in the PVT Growth of Single‐Crystal SiC

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