Basal plane dislocation-free epitaxy of silicon carbide

Zhang, Z.; Sudarshan, Tangali S.

doi:10.1063/1.2093931

Cited by 98 publications

(90 citation statements)

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“…Since E BPD is very close to E TED , 16 It is also demonstrated that the BPD to TED conversion can be enhanced by growth interruptions, 18,19 substrate KOH etching, [20][21][22] or epilayer post annealing. 23 For SiC bipolar power devices, it is required that the BPD to TED conversion occurs in an n + buffer layer (i.e., BPDs are buried in the n + buffer layer.)…”

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confidence: 99%

“…Also the conversion of a BPD to TED is energetically favorable as discussed in detail in a reference. 16 The ratio of elastic energy per unit growth length for a BPD (W BPD ) to that for a TED (W TED ) can be derived from the references 16,17 and written aswhere E BPD and E TED are the elastic energies per unit length of dislocation line for a BPD and a TED respectively, and β is the substrate off-axis angle (≤8 It is also demonstrated that the BPD to TED conversion can be enhanced by growth interruptions, 18,19 substrate KOH etching,[20][21][22] or epilayer post annealing. 23 For SiC bipolar power devices, it is required that the BPD to TED conversion occurs in an n + buffer layer (i.e., BPDs are buried in the n + buffer layer.)…”

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confidence: 99%

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Study of Surface Morphology, Impurity Incorporation and Defect Generation during Homoepitaxial Growth of 4H-SiC Using Dichlorosilane

Song

Chandrashekhar

Sudarshan

2014

ECS J. Solid State Sci. Technol.

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The growth of 4 • off-axis 4H-SiC epilayers by chemical vapor deposition is studied using dichlorosilane as the Si precursor in a chimney reactor. The unintentional and intentional nitrogen doping at various C/Si ratios and N 2 flow rates are investigated. The C/Si ratio has a significant influence on the growth rate, surface morphology, conversion of basal plane dislocations (BPDs), and generation of other defects (e.g., in-growth stacking faults and morphological defects). Addition of N 2 has no obvious influence on growth rate and BPD conversion. It is preferable to grow high quality n + epilayers at a C/Si ratio in the range of 1.3-1.8 along with the addition of a suitable amount of N 2 in consideration of high growth rate, good surface morphology, and low defect density. In this case, the conversion ratio of BPDs to threading edge dislocations is greater than 99.8% regardless of N 2 addition. Therefore >99.8% substrate BPDs can be buried in an n + buffer layer, which is beneficial to SiC bipolar power devices. No special treatment prior to, during or after the epigrowth is necessary. The epilayers with doping concentration all the way from p − (∼1e15 cm −3 ) to semi-insulating, then to n + (∼1e18 cm −3 ), can be achieved, giving a great range of flexibility in growth using dichlorosilane precursor. Further optimization of in-situ etching and growth conditions to eliminate step bunching has also been suggested. 4H-silicon carbide (4H-SiC) is a promising wide bandgap material for high power electronic devices, owing to its unique thermal and electrical properties such as high breakdown field, high thermal conductivity, and high electron saturation velocity.1,2 Chemical vapor deposition (CVD) is a well-developed technique adopted in semiconductor industry to produce high purity and high quality thin films.3 Homoepitaxial growth of SiC via the CVD technique is one of the key steps in the fabrication of high performance SiC devices. Currently, chloride-based CVD has attracted much interest to potentially replace the traditional silane based CVD for SiC epitaxial growth to reduce the Si droplet formation at high growth rates, because of the higher bonding energy of Si-Cl (400 kJ/mol) than SiSi (226 kJ/mol).4 Dichlorosilane (SiH 2 Cl 2 , DCS) is a gas (boiling point: 8.2• C) at room temperature. It has been demonstrated that using DCS and propane (C 3 H 8 ) as the precursors, high crystalline quality 8• off-axis SiC epilayers were achieved at a high growth rate (up to 100 μm/h). 5,6 At present, the standard off-axis angle of commercially available SiC substrates is lowered to 4• to reduce the material loss during substrate preparation from the crystal boules.Step-bunching is a typical surface feature of the epilayers grown on 4• off-axis substrates, resulting in increase in surface roughness. 7Morphological defects, specifically the triangular defects and inverted pyramids, are prone to be generated in epigrowth on low off-axis angle substrates. 8 Hence, determination of optimized growth conditions to produce SiC ...

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confidence: 99%

mentioning

confidence: 99%

Study of Surface Morphology, Impurity Incorporation and Defect Generation during Homoepitaxial Growth of 4H-SiC Using Dichlorosilane

Song

Chandrashekhar

Sudarshan

2014

ECS J. Solid State Sci. Technol.

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“…As mentioned above, the BPD density was 250 cm -2 when the etching time at growth temperature was 12 minutes. It has previously been reported [8] that the creation of BPD etch pits on the substrate surface after molten KOH etching, enhanced the conversion of BPD into TED during epitaxial growth, this effect also increases as the dimension of the BPD etch pits on the substrates became larger. It can thus be speculated that as the etching time increased, the BPD etch pits on the substrates became larger which facilitated the BPD to TED conversion.…”

Section: Resultsmentioning

confidence: 93%

Effect of Process Parameters on Dislocation Density in Thick 4H-SiC Epitaxial Layers Grown by Chloride-Based CVD on 4° Off-Axis Substrates

Yazdanfar

Pedersen

Kordina

et al. 2014

MSF

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“…3 BPDs are present in 4H-SiC substrates with a typical BPD density in the order of 10 4 cm À2 and are able to either propagate to the epitaxial layer or convert to threading edge dislocations (TEDs). [4][5][6] It has been reported that converted BPDs, i.e., TEDs in the epilayer, can be inclined about 20 from the crystallographic c-direction of the crystal. 7,8 Such inclined TEDs are also known as TED II and TED III dislocations and can be identified based on their visibility in x-ray topographs.…”

Section: Introductionmentioning

confidence: 99%

Experimental verification of the model by Klapper for 4H-SiC homoepitaxy on vicinal substrates

Kallinger

Polster

Berwian

et al. 2013

Journal of Applied Physics

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4H-SiC homoepitaxial layers free of basal plane dislocations (BPDs) are urgently needed to overcome the so-called bipolar degradation of high-voltage devices. BPDs being present in substrates are able to either propagate to the epilayer or convert to harmless threading edge dislocations (TEDs) in the epilayer. The model by Klapper predicts the conversion of BPDs to TEDs to be more efficient for growth on vicinal substrates with low off-cut angle. This paper aims to verify the model by Klapper by an extensive variation of epitaxial growth parameters and the substrates' off-cut. It is shown that the off-cut angle is the key parameter for growth of BPD-free epilayers. Furthermore, it is shown that the model also describes adequately the behavior of different types of TEDs, i.e., TED II and TED III dislocations, during epitaxial growth. Therefore, the model by Klapper is verified successfully for 4H-SiC homoepitaxial growth on vicinal substrates. V C 2013 AIP Publishing LLC. [http://dx

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Basal plane dislocation-free epitaxy of silicon carbide

Cited by 98 publications

References 9 publications

Study of Surface Morphology, Impurity Incorporation and Defect Generation during Homoepitaxial Growth of 4H-SiC Using Dichlorosilane

Study of Surface Morphology, Impurity Incorporation and Defect Generation during Homoepitaxial Growth of 4H-SiC Using Dichlorosilane

Effect of Process Parameters on Dislocation Density in Thick 4H-SiC Epitaxial Layers Grown by Chloride-Based CVD on 4° Off-Axis Substrates

Experimental verification of the model by Klapper for 4H-SiC homoepitaxy on vicinal substrates

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