Simulation of isothermal current filament states in GaAs structures

Using 2-D numerical simulation the spatial instability and formation of stable spatial dissipate states (DS) are studied for breakdown of GaAs n-i-n (n-p-n) and Schottky M-i-n structures with long n-layer. It is revealed, that at some value of n-region length the DS is formed spontaneously like a multifilament periodic state. Spatial period of DS is of order of the n-region length and filament dimension of i-region length. Formation and evolution of the multifilament states in the n-i-n GaAs structure corresponds to the experimental data for MESFET and HEMT breakdown in pulse regime.