Abstract
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.
Highlights
The third-generation semiconductor materials have superior physical and chemical properties, such as large forbidden band width, high thermal conductivity, high carrier mobility and high breakdown voltage [1]
Coupled with photo-generated carrier the tested samples is larger than 5 μm, which supports the above conclusion that the LOPCsub peak plasmon, longitudinal optical optical (LO) mode changes to Longitudinal Optical Plasmon Coupled (LOPC) mode
By analyzing the value of K1 for different samples, the effect of the ion-modified layer importantly, it could be shown that Raman scattering measurements with exciting photons having on photo-generated carriers in 4H-Silicon carbide (SiC) can be explained consistently with the trends known from an energy above the band gap of 4H-SiC can be used to determine carrier concentrations of rather literature
Summary
The third-generation semiconductor materials have superior physical and chemical properties, such as large forbidden band width (larger than 2.3 eV), high thermal conductivity, high carrier mobility and high breakdown voltage [1] They can be widely used for devices operating under extreme conditions, such as high temperature, high voltage and high power [2]. The Raman spectrum of a crystallized compound is composed of valuable [10,11].of Conventional methods for measuring the carrier or doping concentration the of internal modes vibration due to the polyatomic species and of external modes characterizing semiconductor materials. By changing attenuator in the optical path, Kyoto, the laser power reaching a pinhole mode,be where the detected volume of the analyzed sample can be the sampleconfocal surface could adjusted to 20 mW, 10 mW,(depth.
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