Abstract
The shrinking channel energy gaps in millimeter-wave heterostructure field-effect transistors (HFETs) make the devices more susceptible to impact ionization. Until recently, the effects of impact ionization on the microwave performance of narrow bandgap channel HFETs have largely been ignored. We studied the effects of impact ionization and quantum confinement on the microwave characteristics of narrow bandgap InAs/AlSb millimeter-wave HFETs. We systematically varied the level of impact ionization in HFETs through channel quantization and bias conditions, and compared the microwave behavior of InAs/AlSb HFETs (with different quantum well widths) to that of conventional GaAs metal semiconductor field effect transistors (MESFETs) fabricated to provide a low ionization benchmark. The observed trends in the S- and Y-parameter data enable us to identify the physical effects of impact ionization on the microwave behavior of narrow-gap channel HFETs. We found that field effect transistor (FET) equivalent circuit models are grossly inadequate when InAs channel HFETs are operated under high impact ionization bias conditions.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call