Optical Characterization of Silicon Carbide Polytypes

Devaty, Robert P.; Choyke, W. J.

doi:10.1002/1521-396x(199707)162:1<5::aid-pssa5>3.0.co;2-j

Cited by 106 publications

(44 citation statements)

References 152 publications

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“…To this end, low-temperature photoluminescence (LTPL) spectroscopy has proved for a long time to be a most convenient and nondestructive technique for the detection and identification of optically activated impurities. [2][3][4][5][6] Basically, in SiC, the group-V substitutional impurities (nitrogen and phosphorus) are donor species while all group-III atoms are acceptors. Among them nitrogen, which is by far the most common residual donor, substitutes on the carbon sites.…”

Section: Introductionmentioning

confidence: 99%

“…Among them nitrogen, which is by far the most common residual donor, substitutes on the carbon sites. 2 On the contrary, based on the size of its covalent radius, 2 phosphorus is expected to substitute preferentially on the silicon sites. The group-III substitutional impurities (Al, Ga, and B) are all potential acceptors and, among them, Al and Ga substitute on the Si sites while B has been demonstrated to reside on C sites, 6 although some authors believe that it may occupy also Si sites.…”

Section: Introductionmentioning

confidence: 99%

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Splitting of type-I (N-B, P-Al) and type-II (N-Al, N-Ga) donor-acceptor pair spectra in 3C-SiC

et al. 2011

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Discrete series of lines have been observed for many years in donor-acceptor pair (DAP) spectra in 3C-SiC. In this work, the splitting of both type-I (N-B, P-Al) and type-II (N-Al, N-Ga) DAP spectra in 3C-SiC has been systematically investigated by considering the multipole terms. For type-I spectra, in which either N or B substitutes on C sites or P and Al replace Si, the splitting energy of the substructure for a given shell is almost the same for both pairs. For type-II spectra, in which N is on the C site while Al and Ga acceptors replace Si, we find that, when compared with literature data, the splitting energy for a given shell is almost independent of the identity of the acceptor. For both type-I and type-II spectra, this splitting energy can be successfully explained by the octupole term V 3 alone with k 3 = −2 × 10 5Å4 meV. Comparing the experimental donor and acceptor binding energies with the values calculated by the effective-mass model, this suggests that the shallow donor (N,P) ions can be treated as point charges while the charge distribution of the acceptor ions (Al,Ga,B) is distorted in accord with the T d point group symmetry, resulting in a considerable value for k 3 . This gives a reasonable explanation for the observed splitting energies for both type-I and type-II DAP spectra.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Splitting of type-I (N-B, P-Al) and type-II (N-Al, N-Ga) donor-acceptor pair spectra in 3C-SiC

et al. 2011

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“…[12][13][14] Quantitative determination of the nitrogen doping concentration [N] using PL in uncompensated n-type 4H-and 6H-SiC has also been reported. [15][16][17] Quantitative determination of shallow impurities in silicon is known for a long time and is based on the fact that the ratio of the integrated PL intensity of the bound to the dopant excitons (BE) to that of free excitons (FE), R = I BE /I FE , is uniquely proportional to the doping concentration.…”

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confidence: 66%

Calibration on wide-ranging aluminum doping concentrations by photoluminescence in high-quality uncompensated p-type 4H-SiC

Asada

Kimoto

Ivanov

2017

Applied Physics Letters

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Previous work has shown that the concentration of shallow dopants in a semiconductor can be estimated from the photoluminescence (PL) spectrum by comparing the intensity of the bound-to-the- dopant exciton emission to that of the free exciton. In this work, we study the low-temperature PL of high-quality uncompensated Al-doped p-type 4H-SiC and propose algorithms for determining the Al-doping concentration using the ratio of the Al-bound to free-exciton emission. We use three different cryogenic temperatures (2, 41, and 79 K) in order to cover the Al-doping range from mid 10(14) cm(-3) up to 10(18) cm(-3). The Al-bound exciton no-phonon lines and the strongest free-exciton replica are used as a measure of the bound-and free-exciton emissions at a given temperature, and clear linear relationships are obtained between their ratio and the Al-concentration at 2, 41, and 79 K. Since nitrogen is a common unintentional donor dopant in SiC, we also discuss the criteria allowing one to determine from the PL spectra whether a sample can be considered as uncompensated or not. Thus, the low-temperature PL provides a convenient non-destructive tool for the evaluation of the Al concentration in 4H-SiC, which probes the concentration locally and, therefore, can also be used for mapping the doping homogeneity. Published by AIP Publishing.

Funding Agencies|Swedish Research Council (VR)

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“…In my study, it was mainly applied to identify SiC polytypes [98], detect impurities and defects [99,100], and quantify the concentration of dopants (for instance, Al and N in SiC) [101,102]. The samples are attached on a holder of the cryostat and could be cooled down to around 2 K by liquid helium.…”

Section: Photoluminescencementioning

confidence: 99%

CVD solutions for new directions in SiC and GaN epitaxy

Li¹

2015

Linköping Studies in Science and Technology. Dissertations

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This thesis aims to develop a chemical vapor deposition (CVD) process for the new directions in both silicon carbon (SiC) and gallium nitride (GaN) epitaxial growth. The properties of the grown epitaxial layers are investigated in detail in order to have a deep understanding. SiC is a promising wide band gap semiconductor material which could be utilized for fabricating high-power and high-frequency devices. 3C-SiC is the only polytype with a cubic structure and has superior physical properties over other common SiC polytypes, such as high hole/electron mobility and low interface trap density with oxide. Due to lack of commercial native substrates, 3C-SiC is mainly grown on the cheap silicon (Si) substrates. However, there’s a large mismatch in both lattice constants and thermal expansion coefficients leading to a high density of defects in the epitaxial layers. In paper 1, the new CVD solution for growing high quality double-position-boundaries free 3C-SiC using on-axis 4H-SiC substrates is presented. Reproducible growth parameters, including temperature, C/Si ratio, ramp-up condition, Si/H2 ratio, N2 addition and pressure, are covered in this study. GaN is another attractive wide band gap semiconductor for power devices and optoelectronic applications. In the GaN-based transistors, carbon is often exploited to dope the buffer layer to be semi-insulating in order to isolate the device active region from the substrate. The conventional way is to use the carbon atoms on the gallium precursor and control the incorporation by tuning the process parameters, e.g. temperature, pressure. However, there’s a risk of obtaining bad morphology and thickness uniformity if the CVD process is not operated in an optimal condition. In addition, carbon source from the graphite insulation and improper coated graphite susceptor may also contribute to the doping in a CVD reactor, which is very difficult to be controlled in a reproducible way. Therefore, in paper 2, intentional carbon doping of (0001) GaN using six hydrocarbon precursors, i.e. methane (CH4), ethylene (C2H4), acetylene (C2H2), propane (C3H8), iso-butane (i-C4H10) and trimethylamine (N(CH3)3), have been explored. In paper 3, propane is chosen for carbon doping when growing the high electron mobility transistor (HEMT) structure on a quarter of 3-inch 4H-SiC wafer. The quality of epitaxial layer and fabricated devices is evaluated. In paper 4, the behaviour of carbon doping using carbon atoms from the gallium precursor, trimethylgallium (Ga(CH3)3), is explained by thermochemical and quantum chemical modelling and compared with the experimental results. GaN is commonly grown on foreign substrates, such as sapphire (Al2O3), Si and SiC, resulting in high stress and high threading dislocation densities. Hence, bulk GaN substrates are preferred for epitaxy. In paper 5, the morphological, structural and luminescence properties of GaN epitaxial layers grown on N-face free-standing GaN substrates are studied since the N-face GaN has advantageous characteristics compared to the Ga...

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Optical Characterization of Silicon Carbide Polytypes

Cited by 106 publications

References 152 publications

Splitting of type-I (N-B, P-Al) and type-II (N-Al, N-Ga) donor-acceptor pair spectra in 3C-SiC

Splitting of type-I (N-B, P-Al) and type-II (N-Al, N-Ga) donor-acceptor pair spectra in 3C-SiC

Calibration on wide-ranging aluminum doping concentrations by photoluminescence in high-quality uncompensated p-type 4H-SiC

CVD solutions for new directions in SiC and GaN epitaxy

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