A perspective on leakage current induced by threading dislocations in 4H-SiC Schottky barrier diodes

Huang, Jhong-Ren; Chen, Ting-Wei; Lee, Jian-Wei; Huang, Chih-Fang; Hong, Lu‐Sheng

doi:10.1016/j.matlet.2021.131506

Cited by 9 publications

(8 citation statements)

References 12 publications

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“…The measured surface potential of the tip is higher than that of the Au tip by 400 mV, with the standard work function of Au being 5.2 eV. With eqs 1 and 2, we find that the local Fermi energies of TSDs and TEDs are 34 The different electronic properties of TDs may be attributed to the different N concentrations in 4H-SiC samples. In our recent work, we find that positively charged N dopants tend to accumulate at the core of BPDs in n-type 4H-SiC and contribute to the donor-like behavior of BPDs in n-type 4H-SiC.…”

Section: Resultsmentioning

confidence: 71%

“…With eqs and , we find that the local Fermi energies of TSDs and TEDs are pinned at the positions of 0.33 eV and 0.78 eV under the conduction band minimum (CBM) of n -type 4H-SiC, respectively. Huang et al found that the local work function decreases in the order of defect-free region, TSD, and TED, indicating that TDs behave as acceptors in 4H-SiC epitaxial layers with the N concentration of 1 × 10 16 cm –3 . The different electronic properties of TDs may be attributed to the different N concentrations in 4H-SiC samples.…”

Section: Resultsmentioning

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: Resultsmentioning

confidence: 71%

Section: Resultsmentioning

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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“…Furthermore, it is argued that the leakage current of threading dislocations, mainly TSDs and TEDs, is dominated by the surface pits formed by the outcrops of the threading dislocations, rather than the threading dislocations themselves (Fiorenza et al, 2020;Fujiwara et al, 2012a;Fujiwara et al, 2012b;Ohtani et al, 2012). However, Huang et al found that the dislocation line of the TED in 4H-SiC Schottky barrier diodes (SBDs) controversially contributes to the leakage current (Huang et al, 2022). Therefore, identifying the degree of the leakage current induced by different types of dislocations, and discriminating the role of dislocations and dislocation-induced pits on the leakage current of 4H-SiC is critical to the optimization of 4H-SiC epilayers.…”

Section: Introductionmentioning

confidence: 99%

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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“…TEDs have been found to increase the leakage current and reduce the breakdown voltage of 4H-SiC diodes. − It was shown that the negative effect of TEDs was induced by surface pits formed by the outcrop of TEDs rather than TEDs themselves. However, a TED without a dislocation-outcrop-induced pit has been found to act as the breakdown point of a metal-oxide-semiconductor capacitor via the Shockley–Read–Hall recombination. , TEDs have also been found to narrow the Schottky barrier and increase the leakage current of a 4H-SiC diode . In addition, it has been demonstrated that impurities can interplay with dislocations, affecting the electronic properties of dislocations in semiconductors. − The concentrations of nitrogen (N) in an n-type 4H-SiC epitaxial layer and an n-type 4H-SiC substrate are in the ranges of 10 14 –10 20 and 10 18 –10 19 cm –3 , respectively .…”

Section: Introductionmentioning

confidence: 99%

“…13,14 TEDs have also been found to narrow the Schottky barrier and increase the leakage current of a 4H-SiC diode. 15 In addition, it has been demonstrated that impurities can interplay with dislocations, affecting the electronic properties of dislocations in semiconductors. 16−19 The concentrations of nitrogen (N) in an n-type 4H-SiC epitaxial layer and an n-type 4H-SiC substrate are in the ranges of 10 14 −10 20 and 10 18 −10 19 cm −3 , respectively.…”

Section: Introductionmentioning

confidence: 99%

Nitrogen-Dependent Electronic Properties of Threading Edge Dislocations in 4H-SiC

Wang

Zhu

et al. 2023

ACS Appl. Electron. Mater.

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The dependence of the electronic properties of threading edge dislocations (TEDs) on the nitrogen (N) doping of 4H silicon carbide (4H-SiC) is investigated by combining first-principles calculations and experiments. First-principles calculations indicate that N atoms tend to accumulate at the cores of TEDs during the N doping of 4H-SiC, giving rise to the formation of TED-N complexes in N-doped 4H-SiC. The accumulation of N donors at the cores of TEDs leads to the donor-like behavior of TEDs in n-type 4H-SiC. With Kelvin probe force microscopy measurements, we verify that TEDs induce acceptor-like and donor-like states in undoped and N-doped 4H-SiC, respectively. For N-doped 4H-SiC, the resistivity decreases when the N concentration increases. In the meantime, the difference in the local Fermi energy between a TED and the perfect 4H-SiC becomes smaller, indicating that the N accumulation at the cores of TEDs may be saturated.

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A perspective on leakage current induced by threading dislocations in 4H-SiC Schottky barrier diodes

Cited by 9 publications

References 12 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

Nitrogen-Dependent Electronic Properties of Threading Edge Dislocations in 4H-SiC

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