Table 2
The formulas of major scattering mechanisms used in 2DEG mobility calculations
Scattering mechanism	Formula	Definition of variables
Acoustic phonon: piezoelectric [15-17]		K, electromagnetic coupling coefficient; JPE(k), electron wave vector dependent integral.
Acoustic phonon: deformation [11,18] potential		ρ, crystal density; vs, longitudinal acoustic phonon velocity; Ξ, deformation potential constant; m*, electron effective mass; JDP(k), electron wave vector dependent integral. b, Fang-Howard expression; qs, reciprocal screening length; f(0), occupation probability; F11(q), ground-state Fang-Howard wave function.
Polar optical phonon [17-19]		, polar optical phonon energy; and , high- and low-frequency dielectric constant; Z0, effective width of triangular well formed at the GaxIn1-xN/GaN interface and is given in terms of Fermi wave vector.
Interface roughness [11,15,20]		Δ, lateral size of the roughness; Λ, correlation length between fluctuations; JIFR(k), correlation length and the lateral size-dependent integral; n2D, 2D electron density.
Alloy disorder [20]		x, Ga fraction; Ω0, the volume occupied by one atom; UA, alloy potential.
Dislocation [21-23]		NDis, dislocation density per unit area which is taken as a fitting parameter; λD, Debye screening length; c, lattice constant of GaxIn1-xN. f, the fraction of filled traps that are assumed fully occupied.

Donmez et al. Nanoscale Research Letters 2012 7:490   doi:10.1186/1556-276X-7-490