Formation of two-dimensional electron gas at AlGaN/GaN heterostructure and the derivation of its sheet density expression*
He Xiao-Guang, Zhao De-Gang†, Jiang De-Sheng
       
Energy band of undoped freestanding AlGaN (taking surface donor states into account). Electrons are stimulated into the conductive band and move under the force of the polarization-induced electric field.