ABSTRACT
An effective method was presented to study impact ionization in GaAs MESFET’s. It was found that the substrate current (Isub) starts flowing at the onset of breakdown on the drain current (IDS). Isub is attributed to hole injection into a semi-insulating GaAs substrate by impact ionization in the channel. To characterize the substrate current and impact ionization theoretically, a simplified model of lateral field distribution in the channel was used. As a result, the ratio of Isub to IDS (Isub/IDS)can be shown to be proportional to an exponential of − 1 / V DS https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003069638/440efdcf-c2ed-414a-bdad-7c98e059177f/content/eq74.tif"/> .
