Influence of a two-dimensional electron gas on current-voltage characteristics of Al0.3Ga0.7 N/GaN high electron mobility transistors

Abstract

The J—V characteristics of AltGa1−tN/GaN high electron mobility transistors (HEMTs) are investigated and simulated using the self-consistent solution of the Schrödinger and Poisson equations for a two-dimensional electron gas (2DEG) in a triangular potential well with the Al mole fraction t = 0.3 as an example. Using a simple analytical model, the electronic drift velocity in a 2DEG channel is obtained. It is found that the current density through the 2DEG channel is on the order of 1013 A/m2 within a very narrow region (about 5 nm). For a current density of 7 × 1013 A/m2 passing through the 2DEG channel with a 2DEG density of above 1.2 × 1017 m−2 under a drain voltage Vds = 1.5 V at room temperature, the barrier thickness Lb should be more than 10 nm and the gate bias must be higher than 2 V.