High-performance highly strained Ga/sub 0.23/In/sub 0.77/As/Al/sub 0.48/In/sub 0.52/As MODFET´s obtained by selective and shallow etch guide recess techniques

Record high f/sub T/L/sub g/ products of 57 and 46 GHz- mu m have been achieved in Ga/sub 1-x/ In/sub x/As/AlInAs MODFETs with a strain compensated channel of x=0.77 and a lattice-matched channel of x=0.53, respectively. Although g/sub m/ as high as 950 mS/mm has been obtained by conventional deep recess for the gate, these latter devices show a prominent kink effect which lowers f/sub T/ and the voltage gain. By limiting the depth of final nonselective recess etch to 3 nm with the help of selective step etches, f/sub T/ as high as 47 GHz and g/sub m/ as high as 843 mS/mm have been achieved for MODFETs with x=0.77 and L/sub g/=1.1 mu m.<>