Composite channel 100 nm InP HEMT with ultrathin barrier for millimetre wave applications

Abstract

This work proposes a new 100 nm InP based InGaAs-InAs-InGaAs composite channel HEMT for millimetre wave applications. The usage of an ultra-thin 2 nm barrier layer, unique composite channel topology and III-V material selection provides superior electron confinement in the channel, enhancing 2DEG concentration and hence, mobility and speed of the proposed device. We achieve a unity current gain frequency (fT) of 248.9 GHz and a maximum oscillation frequency (fMAX) of 523.9 GHz with a current gain of 67.7 dB at 0.1 GHz. Off-state leakage current is in the nanoampere range with minimum noise figure (NFMIN) of only 0.76 dB at 10 GHz. We compare the DC and RF performance and the associated parasitics of different composite channel HEMTs proposed in latest works and mathematically justify why InGaAs-InAs-InGaAs channel HEMTs provide the highest fTand fMAX. InGaAs-InAs-InGaAs channel HEMTs provide 1.4 times better fTand fMAX with only half the NFMINof their InGaAs-InP-InGaAs channel counterparts. A frequency dependent intrinsic FET model is put forward for the proposed HEMT which allows us to model the behavior of the device under varying RF conditions and identify the effect of individual parameters on the entire system.