Analytical Modeling for Off-State Lateral Electric Field and Breakdown Voltage of AlGaN/GaN HEMTs

A physics based model for the off-state lateral electric field in the channel of an AlGaN/GaN High Electron Mobility Transistor (HEMT) is developed by solving 2-D Poisons equation under the gate and considering piecewise linear approximation of the lateral electric field in the depletion region adjacent to the gate edge in drain access region. The model is used to calculate the impact ionisation factor and hence the breakdown voltage of the device. The results obtained from the model show an excellent match with simulation results obtained from Sentaurus TCAD for a wide range of design parameters of the device such as Al-mole fraction in AlGaN barrier layer, as well as gate and drain biases.