Experimental Analysis of Trade-Off Between Transistor Efficiency and Unit Gain Frequency of Nanosheet NMOSFET down to -100 oC

Abstract

This work presents a trade-off analysis between transistor efficiency (gm/I_D which is proportional to the intrinsic voltage gain A_v) and the unit gain frequency (f_T) of nanosheet (NSH) NMOS devices for temperatures from room temperature down to -100 °C. The analyses were performed experimentally as a function of the inversion coefficient (IC) in order to determine the optimal application region for optimization of both parameters. These analyses were performed with NSH NMOS for channel lengths of 28 nm, 70 nm and 200 nm. It was observed that the optimal operation point takes place in the transition between moderate and strong inversion (IC=10) for the three analyzed temperatures, where the highest value obtained for gm/I_D x f_T was found. In this optimum bias point the A_V is 45 dB (L=200 nm) and 39 dB (L=28 nm) and f_T is 9 GHz (L=200 nm) and 186 GHz (L=28nm) both for T=25 °C, which should be suitable for many applications.