Strain-induced v-shaped modulation of hole mobility in GaN

The low hole mobility in wide-bandgap semiconductors remains a critical bottleneck for complementary and high-power electronic devices. Prior first-principles predictions suggested a monotonic increase of over 200% in hole mobility under biaxial tensile strain on the (0001) plane in GaN [Phys. Rev. Lett. 123, 096602 (2019)]. Here, using density functional theory combined with Boltzmann transport formalism, we demonstrate a nonmonotonic, V-shaped modulation of hole mobility as a function of such strain: the overall hole mobility decreases and reaches a minimum at a strain of 0.4--0.5%, then increases at higher strain levels. Our results reveal no enhancement of the in-plane hole mobility under strain up to 1.6%. This nonmonotonic behavior arises from a concurrent evolution of the hole effective masses and hole-phonon scattering rates, both driven by a strain-induced valence-band order inversion. These findings offer critical insights into the interplay between strain and hole transport in wide-bandgap materials and highlight the necessity of precise strain engineering for device performance optimization.