Effect of channel strain on the electrical characteristics of InGaAs/InAlAs HEMTs

In0.52Al0.48As/In0.53+xGa0.47-xAS HEMTs are studied experimentally and theoretically in order to evaluate the effect of strain introduced in the channel by increased In composition. A tight binding formalism is used in order to model the biaxial compressive strain. The distribution of the charge sheet density in the subbands of the quatum well is evaluated as a function of strain and carrier enhancement is observed primarily in the ground state sub-band. Devices were grown by MBE using the presented design procedure. HEMTs were fabricated using 60% and 65% In composition and the measured intrinsic transconductance is found to increase by 40% (321mS/mm) and 47% (359mS/mm) respectively. Capacitance-voltage and temperature characteristics are presented. First microwave results are also reported.