Low frequency and microwave characterization of submicronhyphen;gate In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As heterojunction metalhyphen;semiconductor fieldhyphen;effect transistors grown by molecularhyphen;beam epitaxy

摘要

Dopedhyphen;channelihyphen;In0.52Al0.48As/n+hyphen;In0.53Ga0.47As/ihyphen;In0.52Al0.48As heterojunction metalhyphen;semiconductor fieldhyphen;effect transistors lattice matched to the InP substrates with gate lengths in the submicron range have been fabricated and characterized. The dc and microwave performance of the devices are presented in this paper. Drain current anomalities, or the kink effects, were observed at room temperatures as well as at 77 K in the dc measurements. The kinks are associated with the deephyphen;level electron trapping, and are not present at microwave frequencies. The dc and microwave bias points for achieving maximum transconductance are different. Normal microwave characteristics are exhibited. A compression of transconductancegmis observed in the dc measurement, while suchgmdegradation phenomenon does not appear at microwave frequencies. At 10 GHz, an extrinsicgmof 507 mS/mm, a currenthyphen;gainhyphen;cutoff frequencyftof 49.5 GHz, and a powerhyphen;gainhyphen;cutoff frequency (fmax) of 70.5 GHz were observed for a 0.25hyphen;mgr;mhyphen;gate device. For a 0.3hyphen;mgr;mhyphen;gate device, agmof 545 mS/mm, anftof 42 GHz, and anfmaxof 114 GHz were measured. Output conductance as low as 7.7 mS/mm was measured. A voltage gain (gm/gds) as high as 64 was observed. The voltage gain for measured devices is well above 20 for a wide range of bias conditions. Fabricated devices show their potential for highhyphen;frequency operations. Further investigation of the origin of traps should result in improved lowhyphen;frequency device characteristics.