4H–SiC homoepitaxy on nearly on-axis substrates using TFS-towards high quality epitaxial growth

Balachandran, Anusha; Song, Haizheng; Sudarshan, Tangali S.; Chandrashekhar, M. V. S.

doi:10.1016/j.jcrysgro.2016.05.018

Cited by 13 publications

(10 citation statements)

References 39 publications

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“…It has been shown for fluorinated CVD of SiC on on-axis 4H SiC (0001) substrates that the growth rate is limited by the amount of carbon containing species (C-limited) for higher inlet C/Si ratios. 25 We find, however, that the onset of epitaxial growth also changes with the inlet C/Si ratio as shown in Figure 2, where the onset of epitaxial growth shifts downstream in the susceptor for increased inlet C/Si ratio.…”

Section: Resultsmentioning

confidence: 69%

Silicon Chemistry in Fluorinated Chemical Vapor Deposition of Silicon Carbide

et al. 2017

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The use of chlorinated chemical vapor deposition (CVD) chemistry for growth of homoepitaxial layers of silicon carbide (SiC) has diminished the problem of homogenous gas phase nucleation, mainly the formation of Si droplets, in CVD of SiC by replacing Si-Si bonds with stronger Si-Cl bonds. Employing the even stronger Si-F bond could potentially lead to an even more efficient CVD chemistry, however, fluorinated chemistry is very poorly understood for SiC CVD. Here, we present studies of the poorly understood fluorinated CVD chemistry for homoepitaxial SiC layers using SiF4 as Si precursor. We use a combination of experimental growth studies, thermal equilibrium calculations of gas phase composition and quantum chemical computations (i.e. hybrid density functional theory) of the surface chemistry to probe the silicon chemistry in the CVD process. We show that while growth rates on the order of 35 µm/h can be achieved with a fluorinated chemistry, the deposition chemistry is very sensitive to the mass flows of the precursors and not as robust as the chlorinated CVD chemistry which routinely yields 100 µm/h over wide conditions. By using the position for the onset of epitaxial growth along the gas flow direction as a measurable, together with modeling, we conclude that SiF is the main Si growth species with SiHF as a minor Si species contributing to growth.

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Section: Resultsmentioning

confidence: 69%

Silicon Chemistry in Fluorinated Chemical Vapor Deposition of Silicon Carbide

et al. 2017

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“…EG showed the key Raman peaks at ∼1580, ∼1350, and ∼2650 cm –1 with a D/G ratio of ∼0.1, indicating good quality. The thickness from X-ray photoelectron spectroscopy was ∼15 monolayers. , Individual circular device mesas with diameters ∼250 μm were fabricated by using standard photolithography and O 2 -plasma reactive ion etching.…”

Section: Methodsmentioning

confidence: 99%

“…The thickness from X-ray photoelectron spectroscopy was ∼15 monolayers. 26,30 Individual circular device mesas with diameters ∼250 μm were fabricated by using standard photolithography and O 2 -plasma reactive ion etching.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Photovoltaic and Photoconductive Action Due to PbS Quantum Dots on Graphene/SiC Schottky Diodes from NIR to UV

Kelley

Letton

Simin

et al. 2019

ACS Appl. Electron. Mater.

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We demonstrate photovoltaic and photoconductive responses to near-infrared light in devices formed by depositing a film of gel permeation chromatography purified PbS quantum dots (QDs) on top of n-SiC epitaxial layers with natively grown, low-leakage 10–15 monolayer thick epitaxial graphene (EG) Schottky contacts. The QD film layer was removable by selective chemical etching, resetting the EG/SiC Schottky diode: the sub-bandgap response could be restored in subsequent PbS-QD depositions. The EG in these devices simultaneously forms Schottky contacts to SiC and ohmic contacts to PbS-QD, enabling electrical screening and isolation of these interfaces from each other. After PbS-QD deposition, the diodes exhibit photovoltaic and photoconductive responses at photon energies far below the SiC bandgap, extending to the NIR gap of the QD film. Scanning photocurrent microscopy illustrates that this is due to charge transfer from the QD film to the n-type 4H-SiC through a trap-limited, rectifying PbS-QD/SiC heterojunction with ideality n = 2 in parallel with the EG/SiC Schottky diode. The photoconductive gain at this QD/SiC interface could be useful for IR detection in wide-bandgap platforms. Response times as fast as 40 ms are suitable for imaging applications, although careful contact design is required to optimize work-function matching and spreading resistance.

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“…For on-axis homoepitaxial growth, one of the major challenges has been to control the spontaneous formation of 3C-SiC inclusions on the Si-face of 4H-SiC substrates. − It has been shown that 100% 4H polytype can be obtained in epilayers grown on the Si-face of 2-in. diameter wafers through controlling the substrate’s surface etching and early stage of the growth .…”

Section: Introductionmentioning

confidence: 99%

Wafer Scale On-Axis Homoepitaxial Growth of 4H-SiC(0001) for High-Power Devices: Influence of Different Gas Phase Chemistries and Growth Rate Limitations

Ul-Hassan

Karhu

Lilja

et al. 2019

Crystal Growth & Design

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On-axis homoepitaxy of 4H-SiC has the advantage of producing epilayers that are free of basal plane dislocations. Such layers can be highly beneficial for SiC-based high-power bipolar electronic devices which otherwise suffer from bipolar degradation phenomena related to basal plane dislocations in epilayers. In this study, we have developed on-axis homoepitaxy on the Si-face of 100 mm diameter 4H-SiC wafers with only 4H polytype in the epilayer excluding the edges of the wafer. We have also compared standard and chloride-based growth, the influence of different ambient conditions on surface preparation of the substrate, the influence of the histories of different growth cells, and the geometry of the susceptors regarding 4H-polytype stability in the epilayer. Substrate surface preparation, growth temperature, C/Si ratio, and Si/H ratio are found to be the most influential parameters to achieve homoepitaxy. On-axis homoepitaxial growth rate is limited to a very low value of <10 μm/h. We have performed a systematic study to understand the influence of different growth parameters and gas phase chemistries to determine whether on-axis growth rate can be enhanced and, if not, what the limiting factors are. Our experimental evidence suggests that the on-axis growth rate is not limited by the gas phase chemistry or diffusion, but it is limited by the surface kinetics. A significantly low step density on on-axis substrates lowers the surface reaction rates and limits the growth rate to lower values. It may not be possible to further improve the growth rate even with chloride-based growth using epitaxial growth conditions.

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4H–SiC homoepitaxy on nearly on-axis substrates using TFS-towards high quality epitaxial growth

Abstract: We report high quality homoepitaxial growth on nearly on-axis () 4H-SiC substrates by chemical vapor deposition (CVD) using Tetrafluorosilane and Propane as Si and C-precursors, respectively. N-type unintentional doping (10 17 cm-3 to 10 14 cm-3) was obtained for 0.6 Show more

Cited by 13 publications

References 39 publications

Silicon Chemistry in Fluorinated Chemical Vapor Deposition of Silicon Carbide

Silicon Chemistry in Fluorinated Chemical Vapor Deposition of Silicon Carbide

Photovoltaic and Photoconductive Action Due to PbS Quantum Dots on Graphene/SiC Schottky Diodes from NIR to UV

Wafer Scale On-Axis Homoepitaxial Growth of 4H-SiC(0001) for High-Power Devices: Influence of Different Gas Phase Chemistries and Growth Rate Limitations

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