A Theoretical Calculation of the Impact of GaN Cap and $\hbox{Al}_{x}\hbox{Ga}_{1-x}\hbox{N}$ Barrier Thickness Fluctuations on Two-Dimensional Electron Gas in a $\hbox{GaN}/\hbox{Al}_{x}\hbox{Ga}_{1-x}\hbox{N/GaN}$ Heterostructure

The electron mobility in a 2-D electron gas in a GaN/Al
_x
Ga
_1-x
N/GaN heterostructure limited by GaN cap-thickness-fluctuation (CTF) and Al
_x
Ga
_1-x
N barrier thickness-fluctuation (BTF) scattering is calculated considering the strong spontaneous and piezoelectric polarization. The calculated results reveal that the electron mobility limited by CTF and BTF scattering is lower than that limited by interface roughness scattering if the Al
_x
Ga
_1-x
N barrier layer is thin enough (several nanometers).