Mixed technology of ion implantation and heteroepitaxy: ion-implanted In/sub x/Ga/sub 1-x/As/GaAs MESFETs

State-of-the-art FET performance with f/sub t/'s of 55 and 61 GHz has been achieved using 0.5- mu m-gate In/sub 0.1/Ga/sub 0.9/As and graded In/sub x/Ga/sub 1-x/As MESFETs, respectively. The material growth and device fabrication are described, and the device characteristics are reported. In comparison to the In/sub 0.1/Ga/sub 0.9/As MESFET, the graded-material MESFET shows a better Schottky gate, which is essential for device performance. This novel InGaAs MESFET is of interest for InGaAs-based circuits that are suitable, among other applications, for long-wavelength fiber-optic communication. >