PAM-XIAMEN is able to supply you with P type SiC substrate, more specifications please see: https://www.powerwaywafer.com/p-type-silicon-carbide-substrate-and-igbt-devices.html.

SiC single crystal has the characteristics of wide bandgap, high critical breakdown electric field, high thermal conductivity, high carrier saturation drift speed, and good stability. Among the numerous crystal forms of SiC, 4H-SiC has high electron mobility and weak anisotropy, making it key material for manufacturing high-power power electronic devices that can operate under high voltage.

1. Research Significance of PVT Grown Al Doped P Type SiC Substrate

Normally, the resistivity of 4H-SiC single crystals must be quite low. N-type 4H SiC single crystals with a resistivity of less than 30 mΩ•cm have been prepared using the Physical Vapor Transport (PVT) method, achieving industrial applications. However, for p-type 4H-SiC single crystals with low resistivity, their development lags significantly behind n-type 4H SiC single crystals. So far, the resistivity of p-type 4H SiC single crystals with low resistivity, which are still in the research stage, has not decreased to below 30 mΩ•cm. Especially, the resistivity of p-type 4H SiC single crystals prepared by the industrialized PVT method can often only be reduced to around 100 mΩ•cm. This seriously limits the development of important power devices such as n-channel 4H-SiC insulated gate bipolar transistors (IGBTs) that can operate under high voltage (>10 kV).

2. Research on Compensation Effect in PVT Grown P-Type 4H-SiC

There are two main reasons for limiting the development of p-type 4H SiC with low resistivity. Firstly, incomplete ionization of p-type impurity Al. The ionization energy of Al in 4H-SiC is about 0.23 eV, which results in an ionization rate of only 5% -30% for Al at room temperature. Secondly, there are numerous compensation centers. Although it was once believed that unintentionally doped nitrogen (N) impurities were the main compensation centers, experimental results have shown that the number of compensation centers is often greater than the concentration of N doping. This also means that there are other unknown compensation centers.

Through first principles calculations, it was found that the positively divalent carbon vacancies (VC2+) are a major compensation center in Al doped 4H-SiC. As the concentration of Al doping increases, the formation energy of VC2+decreases, thereby pinning the Fermi level of 4H-SiC at deeper positions. This seriously limits the increase in carrier concentration caused by the increase in Al doping concentration in 4H-SiC, and restricts the preparation of low resistivity p-type 4H SiC. When the concentration of Al doping is very high (≥1020 cm-3), positive trivalent interstitial Al atoms (Ali3+) also appear, which can partially contribute to the compensation effect. The above research results are expected to guide researchers in developing defect control methods for 4H-SiC under non thermodynamic equilibrium conditions, suppressing or even eliminating compensation centers, thereby achieving the preparation of p-type 4H-SiC with low resistivity.

Fig. 1 (a) Schematic diagram of the compensation effect of VC2+and Ali3+on Alsi1-; (b) formation energy diagram of Al, VC, and AlSi-VC complexes calculated by first principles.

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