Top-gated graphene field-effect transistors by low-temperature synthesized SiNx insulator on SiC substrates

• Published in: Japanese Journal of Applied Physics 2016-06, Vol.55 (6S1)
• Main Authors: Ohno, Yasuhide, Kanai, Yasushi, Mori, Yuki, Nagase, Masao, Matsumoto, Kazuhiko
• Format: Article
• Language: English
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.55.06GF09

Top-gated devices made from an epitaxial graphene film on a 4H-SiC substrate were fabricated. Atomic force microscopy and Raman spectroscopy results showed that a large-scale highly uniform monolayer graphene film was synthesized on the SiC substrate. A SiNx passivation film was deposited on a SiC graphene device as a top gate insulator by catalytic chemical-vapor deposition (Cat-CVD) below 65 °C. After the top gate electrode was formed on the SiNx film, no leakage current flowed between the gate and source electrodes. The transport characteristics showed clear ambipolar characteristics from 8 to 280 K, and the temperature dependences of the conductance and field-effect mobility of the devices implied that monolayer graphene devices can be successfully fabricated. Moreover, the position of the charge neutrality point after SiNx deposition was around 0 V, indicating p-doping characteristics. These results indicate that SiNx films synthesized by Cat-CVD can be used as gate insulators and that the carrier type may be controlled by adjusting the deposition conditions.