ABSTRACT
One of the major influences on the NDR(negative differential output resistance) effect of AlGaAs/GaAs HBTs is the surface recombination current. It degrades current gain and affects thermal stability. In this work, we have separated the base current into area and edge current components, and have extracted the formula for each current components. The electro-thermal simulation which satisfies the electrical equations and heat transfer equation has been performed. The electrical equations included the temperature-dependent nonuniform base current and current gain. The simulated result shows a good agreement with measured I-V curve, indicating that the model used in this simulation is useful for analyzing exact thermal behaviors of HBTs.
