Submicrometer p-Type SiGe modulation-doped field-effect transistors for high speed applications

Excellent improvement in the hole transport properties for SiGe heterostructures promises symmetric, higher speed, and lower power consumption circuits compared to conventional Si CMOS devices. Modulation-doped field effect transistors (MODFETs) grown on a relaxed Si0.7Ge0.3 buffer have been fabricated using a self-aligned gate process. The p-type devices had gate lengths ranging from 1.0 μm down to 0.1 μm. A record unity current gain cutoff frequency fT of 70 GHz was obtained for 0.1 μm gate-length devices.