Papers by Keyword: P-Channel MOSFET

Abstract: From a viewpoint of device application using p-channel SiC MOSFETs, control of their channel properties is of great importance. We aimed to control the electrical properties of 4H-SiC p-channel MOSFETs through locating the p-type epitaxial layer at the channel area, so called “epi-channel MOSFET” structure. We varied the dopant concentrations and the thickness of the epi-channel layer, and investigated their electrical properties. In case of heavily doped epi-channel samples, the devices indicated “normally-on” characteristics, and their channel mobility decreased slightly in comparison with the inversion-type devices. As for lightly doped epi-channel samples, the subthreshold current increased with thickness of the epi-channel layer keeping their “normally-off” characteristics. Their channel mobility also increased with thickness of the epi-channel layer. The peak value of field effect channel mobility of the sample with 2.5 μm thickness and 5×1015 /cm3 dopant concentration epi-channel was 18.1 cm2/Vs.

Abstract: It is of great importance to investigate the electrical properties of SiC p-channel MOSFETs for development of SiC CMOS technology. In the present report, we investigated dependences of electrical properties of the SiC p-channel MOSFETs on SiC poly-types. The on-state characteristics (channel mobility, threshold voltage, and temperature dependences) for the 4H- and 6H-SiC p-channel MOSFETs showed similar behavior, although those of 4H-SiC n-channel MOSFETs are usually quite different from those of 6H-SiC. These results might be caused by the similar SiC MOS interface state distribution around the valence band edge.

Abstract: We have fabricated inversion-type p-channel MOSFETs on 4H-SiC substrates. In this paper, influences of gate oxidation process on the properties of p-channel MOSFETs were investigated. The gate oxide was formed under these three conditions: (i) dry oxidation, (ii) dry oxidation following wet re-oxidation, and (iii) wet oxidation. The C-V measurements of p-type 4H-SiC MOS capacitors revealed that wet oxidation process reduced the interface states near the valence band. The p-channel MOSFET with low interface states near the valence band indicated low threshold voltage (Vth), high field effect channel mobility (μFE) and low subthreshold swing (S). We obtained 4H-SiC p-channel MOSFET with high μFE of 15.6cm2/Vs by using wet oxidation as gate oxidation process.