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In this paper, we have investigated 4H-SiC p-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) with deposited SiO2 followed by N2O annealing. In addition to deposited oxides, dry-O2-grown oxides and N2O-grown oxides were also adopted as the gate oxides of SiC p-channel MOSFETs. The MOSFETs have been fabricated on the 4H-SiC (0001), (0001macr), (033macr8), and (112macr0) faces. The (0001) MOSFETs with deposited oxides exhibited a relatively high channel mobility of 10 cm2/V ldr s, although a mobility of 7 cm2/V ldr s was obtained in the (0001) MOSFETs with N2O-grown oxides. The channel mobility was also increased by utilizing the deposited SiO2 in the MOSFETs fabricated on nonbasal faces, although the MOSFETs on (0001macr) were not operational. Compared with the thermally grown oxides, the deposited oxides annealed in N2O are effective in improving the performance of 4H-SiC p-channel MOSFETs.

A magnetron with a metallic cathode shield on the high-voltage (HV) input side is newly designed for the purpose of reducing the spurious noise generated from an oven magnetron. In this paper, it was experimentally found that the newly designed magnetron suppressed the sideband noise around the carrier frequency up to 10 dB, compared to the conventional magnetron. Moreover, both the spurious noise in the high frequency bands (4-14 GHz) and the line noise in the low frequency bands (~1 GHz) from the newly designed magnetron were reduced up to 30 dB, compared to the conventional one. It was also found that a cathode shield attached to only the HV input side was more effective than the cathode shields attached to both the HV input side and the RF output side, with respect to the noise reduction. The thermionic emission from the cathode filament and the motions of the electrons in a magnetron are discussed in investigating the noise-reduction mechanisms