Channel noise in InGaAs/InP composite channel high electron mobility transistors (HEMTs)

High frequency channel noise in InP HEMTs with an InGaAs/InP composite channel has been characterized and analyzed to gain a better understanding on the high frequency noise originating from a more complicated channel structure. The channel noise in the composite channel HEMT shows different drain voltage dependence as compared to the conventional HEMT using a single InGaAs layer as the channel. A reduction of the channel noise at high drain voltage is observed in composite channel. This can be attributed to the suppression of the frequency dependent channel noise component, which is related to the impact ionization in the narrow bandgap InGaAs channel, due to the carrier transfer from InGaAs channel to InP subchannel at high V_d.