Cubic inclusions in 4H-SiC studied with ballistic electron-emission microscopy

Ding, Yun; Park, Kibog; Pelz, J. P.; Palle, K. C.; Mikhov, M. K.; Skromme, Brian; Meidia, Hira; Mahajan, S.

doi:10.1116/1.1705644

Cited by 3 publications

(1 citation statement)

References 28 publications

(27 reference statements)

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“…However, this approach is oversimplified. In the cubic polytype, all the four bonds formed by the |sp 3 orbitals of Si and C are equivalent, whereas in a noncubic, e.g., hexagonal polytype the equivalence is broken [74,81,[124][125][126]. In this case, a charge transfer occurs between the bonds, which leads to a spontaneous polarization P of the medium.…”

Section: Photoluminescence Study Of Nh-sic/3c-sic/nh-sic Quantum Wellsmentioning

confidence: 99%

Heterojunctions and superlattices based on silicon carbide

Лебедев

2006

Semicond. Sci. Technol.

163

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In addition to possessing unique electrical properties, silicon carbide (SiC) can crystallize in different modifications (polytypes). Having the same chemical nature, SiC polytypes may significantly differ in their electrical parameters. In recent years, the world's interest in the fabrication and study of heteropolytype structures based on silicon carbide has considerably increased. This review considers studies concerned with polytypism in SiC, fabrication technologies of various types of heterostructures constituted by different SiC polytypes and their electrical parameters. It is shown that heterostructures between SiC polytypes may have a better structural perfection than those constituted by semiconductors that differ in chemical nature. A conclusion is made that SiC-based heterostructures are promising for application in modern electronic devices.

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Section: Photoluminescence Study Of Nh-sic/3c-sic/nh-sic Quantum Wellsmentioning

confidence: 99%

Heterojunctions and superlattices based on silicon carbide

Лебедев

2006

Semicond. Sci. Technol.

163

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Degradation of hexagonal silicon-carbide-based bipolar devices

Skowroński

2006

Journal of Applied Physics

444

246

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Only a few years ago, an account of degradation of silicon carbide high-voltage p-i-n diodes was presented at the European Conference on Silicon Carbide and Related Compounds (Kloster Banz, Germany, 2000). This report was followed by the intense effort of multiple groups utilizing varied approaches and subsequent progress in both fundamental understanding of this phenomenon and its elimination. The degradation of SiC p-i-n junctions is now well documented to be due to the expansion of Shockley-type stacking faults in the part of the devices reached by the electron-hole plasma. The faults can gradually cover most of the junction area, impeding current flow and, as a result, increasing the on-state resistance. While in most semiconductors stacking faults are electrically inactive, in hexagonal silicon carbide polytypes (4H- and 6H-SiC) they form quantum-well-like electron states observed in luminescence and confirmed by first-principles calculations. The stacking-fault expansion occurs via motion of 30° silicon-core partial dislocations. The Si–Si bond along the dislocation line induces a deep level in the SiC band gap. This state serves as both a radiative and a nonradiative recombination center and converts the electron-hole recombination energy into activation energy for the dislocation motion. Dislocation motion is typically caused by shear stress, but in the case of SiC diodes, the driving force appears to be intrinsic to the material or to the fault itself, i.e., the fault expansion appears to lower the energy of the system. Stable devices can be fabricated by eliminating stacking-fault nucleation sites. The dominant type of such preexisting defects is the segment of basal plane dislocations dissociated into partials. The density of such defects can be reduced to below 1cm−2 by conversion of all basal plane dislocations propagating from the substrate into threading ones in the epitaxial layer. Remarkable progress in fabrication of low basal plane dislocation density material offers hope of bipolar SiC devices being available commercially in the near future.

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Inhomogeneities in Ni∕4H-SiC Schottky barriers: Localized Fermi-level pinning by defect states

Ewing

Porter

Wahab

et al. 2007

Journal of Applied Physics

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We investigated arrays of Ni, Pt, or Ti Schottky diodes on n-type 4H-SiC epitaxial layers using current-voltage (I-V) measurements, electron beam induced current (EBIC), polarized light microscopy, x-ray topography, and depth-resolved cathodoluminescence spectroscopy. A significant percentage of diodes (∼7%–30% depending on epitaxial growth method and diode size) displayed “nonideal” or inhomogeneous barrier height characteristics. We used a thermionic emission model based on two parallel diodes to determine the barrier heights and ideality factors of high- and low-barrier regions within individual nonideal diodes. Whereas high-barrier barrier heights increased with metal work function, low-barrier barrier heights remained constant at ∼0.60, 0.85, and 1.05eV. The sources of these nonidealities were investigated with a variety of spectroscopic and imaging techniques to determine the nature and energy levels of the defects. EBIC indicated that clusters of defects occurred in all inhomogeneous diodes. Cathodoluminescence spectra revealed additional peaks in the nonideal diodes at 2.65, 2.40, and 2.20eV, which complement the low-barrier barrier heights. It is proposed that defect clusters act to locally pin the Fermi level, creating localized low-barrier patches, which account for the inhomogeneous electrical characteristics.

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Cubic inclusions in 4H-SiC studied with ballistic electron-emission microscopy

Cited by 3 publications

References 28 publications

Heterojunctions and superlattices based on silicon carbide

Heterojunctions and superlattices based on silicon carbide

Degradation of hexagonal silicon-carbide-based bipolar devices

Inhomogeneities in Ni∕4H-SiC Schottky barriers: Localized Fermi-level pinning by defect states

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