Current instability and burnout under MESFET gate breakdown

The gate burnout (irreversible breakdown) of GaAs MESFET has been studied using two-dimensional (2-D) numerical simulation and experimental measurements of 10 ns pulsed gate-source I-V characteristics. It is shown, that at some critical level of gate avalanche current the gate current instability appears. The instability results in formation of a negative differential conductivity (NDC) region on the S-shape gate-source I-V characteristic, spatial instability of avalanche current and formation of high density current filaments

Formation and evolution of spatial dissipate structures in GaAs n-i-n structures

On the basis of two-dimensional numerical simulation the formation, evolution and kinetics of spatial dissipative structures (DS) under breakdown of GaAs n-i-n structure are studied. It is found, that at some critical length of the n-GaAs layer the instability of spatial distribution of the current along contacts results in the formation of spatial periodic structures as multiple current filaments. With current increase the spatial period of DS decreases down to some minimum value. It is revealed that physically DS formation is the result of a distinction between a small spatial parameter of instability (due to avalanche-injection modulation of i-region conductivity) and a large spatial parameter of current damping (due to current spreading in the lengthy n-contact region)