Investigation on the sources of 2DEG in AlxGa1-xN/GaN HEMT

The AlGaN/GaN HEMTs have many advantages for high frequency and high power applications because of its unique material properties. In this paper, AlGaN/GaN HEMT has been investigated through computer simulation including spontaneous and piezoelectric polarization charges. By self-consistently solving the Schrodinger-Poisson equations, the information of electron distribution, density of 2DEG and electric field are obtained. In addition, the electronic tunneling probability of wz-GaN induced by strong interface electric field is discussed. The simulation result shows that the tunneling charge in GaN channel layer is an important source of 2DEG besides the unintentional donor impurity in GaN channel layer and the ionized donor in AlGaN barrier layer. Moreover the ratio of tunneling charges to 2DEG increases with the improvement of Al composition.