Influence of a two-dimensional electron gas on current–voltage characteristics of Al_0.3Ga_0.7 N/GaN high electron mobility transistors

The J-V characteristics of Al_tGa_1-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 \times 10¹³ A/m² passing through the 2DEG channel with a 2DEG density of above 1.2 \times 10¹⁷ m^-2 under a drain voltage V_ds=1.5 V at room temperature, the barrier thickness L_b should be more than 10 nm and the gate bias must be higher than 2 V.