Jul 15, 2015

Characterization of defects in n-type 4H-SiC after high-energy N ion implantation by RBS-channeling and Raman spectroscopy

Implantation with 1 MeV N ions was performed at room temperature in n-type 4H-SiC (0 0 0 1) at four implantation fluences (or doses in dpa (displacements per atom) at the damage peak) of 1.5 × 1013 (0.0034), 7.8 × 1013 (0.018), 1.5 × 1014 (0.034), and 7.8 × 1014(0.178) ions/cm2, respectively. The evolution of disorder was studied using Rutherford backscattering spectrometry in channeling mode (RBS-C), Raman spectroscopy, and optical transmission. The disorder in the Si sub-lattice was found to be less than 10% for the dpa of 0.0034 and 0.0178 and increased to 40% and 60% for the dpa of 0.034 and 0.178 respectively. The normalized Raman intensity In, shows disorder of 41%, 69%, 77% and 100% for the dpa of 0.0034, 0.0178, 0.034 and 0.178, respectively. In this paper, the characterization of the defects produced due to the nitrogen implantation in 4H-SiC are presented and the results are discussed.


Jul 1, 2015

Hall-effect characterization of electron transport at SiO2/4H-SiC MOS interfaces

• Inversion layer transport parameters determined using mobility spectrum analysis.
Mobility extracted from both normally-on and normally-off 4H-SiC MOS structures.
Broad inversion layer mobility distribution indicates scattering factor >1.
Trapping at interface reduces the inversion layer free electron sheet density.

Magnetic-field dependent resistivity and Hall-effect measurements combined with high resolution mobility spectrum analysis (HR-MSA) were employed to study room-temperature electronic transport in 4H-SiC metal–oxide–semiconductor field-effect transistor (MOSFET) structures. It is shown that the mobility distribution for electrons at the SiO2/SiC interface is significantly broader than expected for quantum confined carriers, exhibiting Hall scattering factors significantly greater than the generally assumed unity value. The interfacial electron mobility and Hall scattering factor are likely to be determined by potential fluctuations arising from a disordered transition layer on the SiC side of the SiO2/SiC interface. For the MOSFET structures studied, charge trapping at the SiO2/SiC interface was found to determine the interfacial free electron sheet density, in agreement with prior studies on similar device structures. HR-MSA has enabled unambiguous discrimination between electrons in the ion-implanted buried channel layer and at SiO2/SiC interface in a depletion-mode MOSFET structure.

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