Ga0.4In0.6As/Al0.55In0.45As pseudomorphic modulation-doped field-effect transistors

High-performance pseudomorphic Ga
0.4
In
0.6
As/ Al
0.55
In
0.45
As modulation-doped field-effect transistors (MODFET's) grown by MBE on InP have been fabricated and characterized. DC transconductances as high as 271, 227, and 197 mS/mm were obtained at 300K for 1.6-µm and 2.9-µm gate-length enhancement-mode and 2-µm depletion-mode devices, respectively. An average electron velocity as high as 2.36 × 10
⁷
cm/s has been inferred for the 1.6-µm devices, which is higher than previously reported values for 1-µm gate-length Ga
0.47
In
0.53
As/Al
0.48
In
0.52
As MODFET's. The higher bandgap Al
0.55
In
0.45
As pseudomorphic barrier also offers the advantages of a larger conduction-band discontinuity and a higher Schottky barrier height.