ABSTRACT
The AlGaN/GaN high-electron-mobility transistor (HEMT) has become a very promising candidate for next-generation semiconductor devices. In the sphalerite structure crystal, the positive and negative ion centers are coincident. However, the positive ion center of the wurtzite crystal structure is not coincident with the negative ion center, and there is a shift along the c axis. Thus GaN with wurtzite crystals has a spontaneous polarization characteristic. The Ga-face AlGaN/GaN heterojunction in which the spontaneous polarization vector is top down. As the lattice constant of AlGaN is smaller than that of GaN, the AlGaN layer is under tensile strain at the upper surface of GaN and the piezoelectric polarization vector (PPE) is also top down. The source field plate also induces an additional electric peak at the terminal of the plate, which can restrain the field peak at the edge of gate to the drain side.
