Simulation of the GaAs mesfet burnout

Electrical breakdown in GaAs MESFETs and GaAs n+-i-n+ structures have been simulated by two-dimentional (2-D) quasi hydrodynamic isothermal model with two types of carriers under "mixed" boundary conditions on the contacts - fixed drain current and fixed gate bias. It has been shown, that when some maximum drain voltage is reached the MESFETs differential conductivity becomes negative at every gate bias. It has been shown that negative differential conductivity (NDC) and filament formation of high current density are the properties of GaAs n+-i-n+ structures breakdown. The negative differential conductivity (NDC) is caused by the electric field reconstruction in the buffer (i layer) by the injected carrier space charge. It is shown, that the suggested breakdown model corresponds to the experimentally observed properties of the drain breakdown of the GaAs MESFET. The electrical burnout mechanism of the power GaAs MESFET under the drain breakdown is explained by the uncontrollable drain current increase due to the NDC and filament formation.