Proceedings of the Second European Workshop on Low Temperature Electronics
J. Phys. IV France 06 (1996) C3-73-C3-78
Threshold Voltage Characteristics of Superconductor Gate nMOSFET at 4.2 KI. Kurosawa1, M. Maezawa1, M. Aoyagi1, H. Nakagawa1, K. Yamamoto2 and S. Matsumoto2
1 Electrotechnical Laboratory, 1-1-4 Umezono, Tsukuba, Ibaraki 305, Japan
2 Keio University, Hiyoshi, Yokohama 223, Japan
We propose a high mobility superconductor gate nMOSFET using undoped Si as the substrate. We have studied superconducting NbN gate nMOSFETs fabricated on p-type Si, undoped Si and n-type Si substrate, respectively. The nMOSFETs on undoped Si and n-type Si have operated properly at 4.2 K. The transconductance of nMOSFETs on undoped Si substrate is higher than that of nMOSFET on p-type Si. The difference in transconductance is attributed to the difference of impurity density in channels. The observed threshold voltages of NbN gate nMOSFETs on p-type Si, undoped Si and n-type Si have little difference at 4.2K.
© EDP Sciences 1996