Self-heating effects in silicon carbide MESFETs

Silicon carbide materials offer specific advantages to MESFET applications. However, to put them to good use requires to apply higher drain voltages than in GaAs devices. Therefore, in spite of the high thermal conductivity of the SiC substrates, this leads to a large power dissipation and a substantial increase in the local temperature. Depending on the device configuration, this self-heating can induce a negative differential conductance at very low frequency near dc regime. A simple analytical model is proposed, which yields a reasonable fit of the MESFET static characteristics. Further experimental evidence for such effects is also given, which corroborates the predictions of the model.