Metamorphic InAlAs/InGaAs HEMT's on GaAs substrates using an InP buffer layer

An AlInAs/InGaAs metamorphic high electron mobility transistor (MM-HEMT) with a pseudomorphic InGaAs channel has been developed on GaAs substrate via an InP buffer layer. The as grown InP layer on GaAs exhibits state of the art structural and electrical properties. The full width at half maximum (FWHM) of the X-ray rocking curve is as small as 370 arcsec. A 0.33 /spl mu/m gate length device fabricated on such an InP/GaAs heterostructure exhibits a current gain cut-off frequency f/sub T/ of 65 GHz and a maximum frequency of oscillation of 105 GHz, both measured at V/sub ds/=1.75 V and V/sub gs/=-0.8 V. Further improvement of the device performance by the introduction of strained layer superlattices (SLS) seems possible and will be discussed.