Direct ion-implanted GaAs MESFET’s are the most attractive devices for microwave, millimeter-wave, and digital integrated circuit applications due to the affordability, availability, reliability, and manufacturability of ion implantation technology. This paper presents and reviews the recent advances in high-speed and ultra-low-noise performance of GaAs MESFET’s. We present experimental results that the current gain cutoff frequency and noise figure achieved by direct ion-implanted GaAs MESFET’s are equal to or better than those achieved by GaAs HEMT’s. Furthermore, we have performed detailed cryogenic-temperature microwave measurements of F, on HEMT’s and MESFET’s and find a similar dependence of the effective velocity with temperature. We conclude that the transport properties of the high electron mobility in the twodimensional electron gas in HEMT’s have been misinterpreted for high-speed device operation, and the high-field velocity is the most important parameter for high-speed device operation. It is the fundamental T-L valley separation of the material and associated effectiveness, either GaAs or InGaAs, which limits the high-field velocity and thus speed of the devices.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering