0.32 μm gate length InP-channel MODFETS with ft above 90 GHz

Abstract

The fabrication and characterisation of high performance InAlAs/InP modulation-doped field-effect transistors (MODFETs) with 0.32 mu m gate lengths are reported. Devices have been fabricated on two different delta-doped heterostructures with one having an extra delta-doping plane just below the cap layer. The extra doping resulted in devices with lower source and drain parasitic resistances. Extrinsic DC transconductances g/sub m/as high as 805 mS/mm and unity current-gain cutoff frequency f/sub t/ as high as 92 GHz obtained for these devices at a drain-to-source voltage V/sub ds/ of 2V are attributed to the low parasitics. Also, the devices exhibited an f/sub t/ of at least 75 GHz up to a V/sub ds/ of 4 V.