Gds and fT analysis of pseudomorphic MODFETs with gate lengths down to 0.1 mym

Developing circuits for higher frequencies requires not only shorter gate lengths (l sub g), but also proper scaling of the epilayer structure. A common problem with reducing only l sub g is increasing output conductance (g sub ds), thus no f sub max improvement is achieved. To quantify the effect of scaling on MODFET performance a set of pseudomorphic MODFETs with different epilayer structures and gate lengths between 1 mym and 0.1 mym were investigated. A linear dependence of the intrinsic output resistance as a function of aspect ratio was derived. In addition no velocity overshoot was observed when analyzing f sub T l sub g. These results indicate that simple scaling rules can be applied to gate lengths even down to 0.1 mym.