0.2μm T-gate InP/InGaAs/ InP pHEMT with an InGaP diffusion barrier layer grown by LP-MOCVD using an N2-carrier

We report on the development of an Al-free InP/InGaAs/InP HEMT that is grown by LP-MOCVD using an N2 carrier. We demonstrate that Zn diffusion affects the performance of those HEMTs and can be reduced by inserting an In0.5Ga0.5P diffusion barrier layer. Devices with a 0.2μm T-Gate yield the cutoff frequencies of fT= 135GHz and fmax= 200GHz. The performance especially of fmax is limited by the high output conductance and can be improved by reducing the In content of the channel from 77% to 68%.