n- and p-type SiGe HFETs and circuits

n- and p-Type SiGe HFETs exhibit advanced performance especially favourable for RF-applications. Due to strained channels high carrier mobilities at r oom temperature (2700 and 1870 cm(2)/V s) and large sheet carrier densities (n(s) = 6.4 x 10(12) cm(x2) and p(s) = 2.1 x 10(12) cm(x2)) have been achi eved. For the n-MODFET (L-G > = 150 nm) tensile strained Si channels embedd ed in Sice layers lead to a maximal g(me) of 476 mS/mm and to cut-off frequ encies of f(t) = 43 GHz and f(max) = 92 GHz. The best results for p-type HF ETs were attained for a pure Ge channel MODFET with f(t) = 32 GHz and f(max ) = 85 GHz. Analog and digital circuit realizations for the n-MODFET result ed in a transimpedance amplifier yielding a Z(21) Of 56 dB Omega at a bandw idth of 1.8 GHz and an inverter with a gate delay of 25 ps. (C) 1999 Elsevi er Science Ltd. All rights reserved.