A Pedagogical Perspective on Ambipolar FETs

The operation of an ambipolar field-effect transistor (FET) is described using a simple diagram depicting the gate voltage and channel potential profile relative to the injection threshold voltage of charge carriers. From this diagram, the transition between transistor-operation regimes and the resulting current-voltage relations can be easily understood. Also, a practical guidance for the operation of an ambipolar FET is provided. In particular, conditions to achieve the true ambipolar regime, which is of particular interest for light-emitting transistor operation, and a correct method to extract electron and hole mobilities from a given current-voltage curve are presented.