Effect of isotope on lattice thermal conductivity of lateral epitaxial overgrown GaN

A theoretical model of the lattice thermal conductivity of GaN is presented on the dependence of isotope abundance and impurity. By using a modified Callaway's model, the thermal conductivity is evaluated and compared with experimental data. The effect of isotope, dislocation and impurity are all taken into account. It is found that there are critical values of impurity concentration and dislocation density below which the isotope effect on conductivity has to be considered and beyond which impurity and dislocation have significant impact. For LEO GaN with a lower dislocation density than normal GaN, the effect of the isotope becomes significant rather than negligible especially in the mask area which has a low dislocation density.