0.32-MU-M GATE LENGTH INP-CHANNEL MODFETS WITH FT ABOVE 90 GHZ

The fabrication and characterisation of high performance InAlAs/InP mo dulation-doped field-effect transistors (MODFETs) with 0.32 mum gate l engths arc reported. Devices have been fabricated on two different del ta-doped heterostructures with one having an extra delta-doping plane just below the cap layer. The extra doping resulted in devices with lo wer source and drain parasitic resistances. Extrinsic DC transconducta nces g(m) as high as 805mS/mm and unity current-pin cut-off frequency f(t) as high as 92 GHz obtained for these devices at a drain-to-source voltage V(ds) of 2V are attributed to the low parasitics. Also, these devices exhibited an f(t) of at least 75 GHz up to a V(ds) of 4 V.