Shock-induced band-gap shift in GaN: Anisotropy of the deformation potentials

The band-gap shift of GaN has been examined as a function of uniaxial compression along the c axis using time-resolved, optical absorption measurements in shock wave experiments. The hydrostatic deformation potential acz-D₁ (parallel to the c axis), has been determined independently from act-D₂ (perpendicular to the c axis). Based on the experimental results, a set of deformation potentials has been obtained: acz-D₁=-9.60.3em0exeV, act-D₂=-8.20.3em0exeV, D₃=1.90.3em0exeV, and D₄=-1.00.3em0exeV. These values indicate that the deformation potentials in wurtzite GaN are anisotropic.