N-polar GaN high-electron-mobility transistors (HEMTs) show unique transfer characteristics originating from the band structure related to the inverted HEMTs, and some scattering mechanisms are suggested theoretically. However, their experimental verification has not been sufficiently discussed yet. In this paper, we compared the experimentally obtained field-effect mobilities of N-polar and Ga-polar GaN HEMTs with each calculated scattering component using the self-consistent 1-dimensional Poisson–Schrödinger calculation, revealing the origin of the differences as the distance between the 2DEG centroid and the GaN/AlN or AlN/GaN interface. Mobility of Ga-polar GaN HEMT was superior to N-polar HEMT despite 2.5 times higher scattering center density, and the highly narrowed quantum well of N-polar GaN HEMT was the dominant factor.
Mukai et al. (Sun,) studied this question.