Raman Spectroscopy Characterization of Ion Implanted 4H-SiC

et al. 2020

Crystals

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For silicon carbide (SiC) processed by ion-implantation, dedicated test structure fabrication or destructive sample processing on test wafers are usually required to obtain depth profiles of electrical characteristics such as carrier concentration. In this study, a rapid and non-destructive approach for depth profiling is presented that uses confocal Raman microscopy. As an example, a 4H–SiC substrate with an epitaxial layer of several micrometers thick and top layer in nanoscale that was modified by ion-implantation was characterized. From the Raman depth profiling, longitudinal optical (LO) mode from the epitaxial layer and longitudinal optical phonon-plasmon coupled (LOPC) mode from the substrate layer can be sensitively distinguished at the interface. The position profile of the LOPC peak intensity in the depth direction was found to be effective in estimating the thickness of the epitaxial layer. For three kinds of epitaxial layer with thicknesses of 5.3 μm, 6 μm, and 7.5 μm, the average deviations of the Raman depth analysis were −1.7 μm, −1.2 μm, and −1.4 μm, respectively. Moreover, when moving the focal plane from the heavily doped sample (~1018 cm−3) to the epitaxial layer (~1016 cm−3), the LOPC peak showed a blue shift. The twice travel of the photon (excitation and collection) through the ion-implanted layer with doping concentrations higher than 1 × 1018 cm−3 led to a difference in the LOPC peak position for samples with the same epitaxial layer and substrate layer. Furthermore, the influences of the setup in terms of pinhole size and numerical aperture of objective lens on the depth profiling results were studied. Different from other research on Raman depth profiling, the 50× long working distance objective lens (50L× lens) was found more suitable than the 100× lens for the depth analysis 4H–SiC with a multi-layer structure.

Section: Depth Profiling Of Net Doping Concentrationsupporting

confidence: 89%

Section: Depth Profiling Set-upsmentioning

confidence: 99%

Depth Profiling of Ion-Implanted 4H–SiC Using Confocal Raman Spectroscopy

Song

et al. 2020

Crystals

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“…On the other hand, due to the smaller energy gap to the valence band and a strong tendency to occupy atomic sites in the silicon sublattice [5,6], and since Al does not appear an abnormal out-diffusion phenomenon as B-doped SiC during annealing [7], Al is preferred. Influenced by constraints such as doping amount and impurity atomic distribution, lowresistance p-type SiC preparation is still a difficult problem to be solved [8], because of ion implantation-induced defects which severely limit carrier lifetime and the effectiveness of doping [9]. Korsunska et al [10] found the recombination centers in 4H-SiC using photoluminescence (PL) spectra.…”

Section: Introductionmentioning

confidence: 99%

MD simulation study on defect evolution and doping efficiency of p-type doping of 3C-SiC by Al ion implantation with subsequent annealing

et al. 2021

J. Mater. Chem. C

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“…The samples were further modified by Al or N ion implantation. More details on the preparation of samples Q1, Q4 and Q3 can be found elsewhere [24] and samples epi, A-N and A-P were prepared similarly. The thickness of the layer modified by ion implantation was approximately 300 nm.…”

Section: Sample Descriptionmentioning

confidence: 99%

Raman Characterization of Carrier Concentrations of Al-implanted 4H-SiC with Low Carrier Concentration by Photo-Generated Carrier Effect

Rommel

et al. 2019

Crystals

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In this work, 4H SiC samples with a multilayer structure (shallow implanted layer in a lowly doped n-type epitaxial layer grown on a highly doped thick substrate) were investigated by Raman scattering. First, Raman depth profiling was performed to identify characteristic peaks for the different layers. Then, Raman scattering was used to characterize the carrier concentration of the samples. In contrast to the conventional Raman scattering measuring method of the Longitudinal Optical Plasmon Coupled (LOPC) mode, which is only suitable to characterize carrier concentrations in the range from 2 × 1016 to 5 × 1018 cm−3, in this work, Raman scattering, which is based on exciting photons with an energy above the band gap of 4H-SiC, was used. The proposed method was evaluated and approved for different Al-implanted samples. It was found that with increasing laser power the Al-implanted layers lead to a consistent redshift of the LOPC Raman peak compared to the peak of the non-implanted layer, which might be explained by a consistent change in effective photo-generated carrier concentration. Besides, it could be demonstrated that the lower concentration limit of the conventional approach can be extended to a value of 5 × 1015 cm−3 with the approach presented here.