Dual-MOSFET structure for suppression of kink in SOI MOSFETs at room and liquid helium temperatures

The dual-MOSFET structure proposed consists of two SOI nMOSFETs, T/sub 1/ and T/sub 2/, in series, but measured as a single device (T/sub 1/ to the source and T/sub 2/ to the drain) with a common gate electrode. The N/sup +/ region in between T/sub 1/ and T/sub 2/ is kept floating. This structure can confine the kink effect to the upper transistor T/sub 2/ and thus successfully keeps the lower transistor T/sub 1/ from undergoing pinch-off, impact ionization, and the kink effect. If the channel length of T/sub 1/ is longer than that of T/sub 2/, then T/sub 1/ will dominate the overall output characteristics of the device. As a result, the kink effect is eliminated from the overall output characteristics. This structure can also confine the parasitic bipolar effect only to the upper transistor T/sub 2/. Since the base hole current of T/sub 2/ will recombine in the common N/sup +/ region, it cannot reach the base region of the lower transistor T/sub 1/. Results of measurements and simulation are given.<
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