ABSTRACT
Silicon Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) dominate modern microelectronics. Gallium Arsenide Metal Semiconductor Field Effect Transistors (GaAs MESFETs) are “runners-up,” and they find many important niche applications in high-speed or high-frequency circuits. After the first successful fabrication of GaAs MESFETs by Mead in 19661 and after the demonstration of their performance at microwave frequencies in 1967 by Hooper and Lehrer,2 these devices emerged as contenders to silicon MOSFETs, bipolar transistors, and High-Electron Mobility Transistors. In the late 1970s and early 1980s, high-quality semiinsulating substrates and ion-implantation processing techniques made it possible to fabricate GaAs MESFET VLSI, such as 16 × 16 multiplier with a multiplication time of 10.5 ns and less than 1 W power dissipation.3 More recently, CMOS and SiGe displaced GaAs MESFETs from digital electronics applications. However, these devices are still being widely used in analog RF electronics, because they have a relatively low noise and a high product of the cutoff frequency times the breakdown voltage. For example, Fujitsu has a 240 W output device in mass production operating at 2.14 GHz with the power-added efficiency of 54%.
