Thermal modeling of power gallium arsenide microwave integrated circuits

Manufacturers are developing power devices for ever higher frequencies using GaAs MESFETs and heterojunction bipolar devices constructed with III-V compounds on GaAs substrates, as well as integrated power devices on monolithic microwave integrated circuits (MMICs). A problem with the technology is the low thermal conductivity of gallium arsenide, giving rise to thermal design problems that must be solved if good reliability is to be achieved. A three-dimensional numerical simulator is used to study this problem. In particular, the approximations which are possible in performing realistic assessments of the thermal resistance of typical GaAs power device structures under steady-state conditions are examined