Strain engineered pHEMTs on virtual substrates: a Monte Carlo simulation study

Monte Carlo simulations are used to investigate the influence of various strain conditions on the performance of pseudomorphic High Electron Mobility Transistors (pHEMTs) with low In content InxGa1-xAs channels (x < 0.3) grown on strain relief graded buffers, commonly referred to as 'virtual' substrates. Strain engineering can be achieved by varying the composition of the graded InxAl1-xAs buffers to control the type and magnitude of strain induced in the channel. It is shown that devices with relaxed (lattice matched) and tensile strained channels provide better RF performance compared with conventional compressively strained pHEMTs on standard GaAs substrates. It is argued that strain engineering in GaAs based devices with low In content in the channel makes it possible to achieve RF performance comparable to that of InP based pHEMTs, whilst improving device breakdown characteristics and avoiding the fabrication problems associated with fragile InP substrates. (C) 1999 Elsevier Science Ltd. All rights reserved.