Charge control and electron transport properties in In/sub y/Al/sub 1-y/As/In/sub x/Ga/sub 1-x/As metamorphic HEMTs: effect of indium content

In/sub y/Al/sub 1-y/As/In/sub x/Ga/sub 1-x/As High Electron Mobility Transistor heterostructures have been grown lattice mismatched on GaAs substrates. These metamorphic HEMTs have been grown by molecular beam epitaxy with various indium molar fractions, from 0.3 to 0.52. The dependence of the density of electrons into the channel and its control by a gate have been investigated as well as low and high electric field transport properties. In particular, the contribution of the electron density to the formation of the drain current has been separated from the saturation velocity. The present results show the interest of growing structures in the 0.4 indium molar fraction region for both low noise and power applications at high frequencies.