Spatial Localization of Carrier Traps in 4H-SiC MOSFET Devices Using Thermally Stimulated Current
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Carrier traps in 4H-SiC metal–oxide–semiconductor (MOS) capacitor and transistor devices were studied using the thermally stimulated current (TSC) method. TSC spectra from p-type MOS capacitors and n-channel MOS field-effect transistors (MOSFETs) indicated the presence of oxide traps with peak emission around 55 K. An additional peak near 80 K was observed due to acceptor activation and hole traps near the interface. The physical location of the traps in the devices was deduced using a localized electric field approach. The density of hole traps contributing to the 80-K peak was separated from the acceptor trap density using a gamma-ray irradiation method. As a result, hole trap density of Nt,hole = 2.08 × 1015 cm−3 at 2 MV/cm gate field and Nt,hole = 2.5 × 1016 cm−3 at 4.5 MV/cm gate field was extracted from the 80-K TSC spectra. Measurements of the source-body n+–p junction suggested the presence of implantation damage in the space-charge region, as well as defect states near the n+ SiC substrate.
KeywordsThermally stimulated current hole traps 4H-SiC MOSCAP 4H-SiC MOSFET threshold voltage implantation damage acceptor activation
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