A low temperature de and HF investigation of 0.25 mu m T-gate Si/Si0.55Ge0.
45 n-MODFET's is presented. Outstanding maximum oscillation frequencies f(m
ax) range from 100-120 GHz at 300 K up to 195 GHz at 50 K. These high-frequ
ency characteristics are the first reported at low temperature on Si/SiGe n
-MODFET's and are also the highest room temperature data reported so far. P
hysical modeling is used to explain the main trends observed when cooling d
own the n-MODFET. Many experimental data are presented, The dependence on t
emperature and biases of the important small-signal equivalent circuit para
meters is investigated to analyze the device high-frequency performances an
d the minimum noise figure of the intrinsic device is determined.