New GaInAs/InAs/InP Composite Channels for mm-Wave Low-Noise InP HEMTs

InP-based HEMTs with composite GaInAs/InAs channels are recognized for their high frequency performance thanks to their superior carrier transport properties. On the other hand, the addition of an InP subchannel to a GaInAs channel can effectively suppress channel impact ionization, lower the output conductance, and improve noise properties. Although the literature provides a number of reports about both separate approaches, we merge both strategies in the present study and report the first GaInAs/InAs/InP composite channel HEMTs. The influence of the InAs inset location is studied through DC, RF and noise characterization. Devices with the InAs inset located further from the top AlInAs barrier exhibit an improved minimum noise figure NFMIN due to a reduced gate leakage current. The NFMIN improvement is accompanied by a slight degradation in both the output characteristics and cutoff frequencies resulting from the increased average gate-to-2DEG separation. Our results indicate that the combination of an InAs inset and an InP subchannel opens promising HEMT design avenues for broadband low-noise applications.