The emission properties of bent ZnO microwires with diameters ranging from 1.5 μm to 7.3 μm are
systematically investigated by cathodoluminescence spectroscopy at T ≈ 10 K. We induced
uniaxial strains along the c-axis of up to ±2.9 %. At these high strain values, we observe a nonlinear
shift of the emission energy with respect to the induced strain, and the magnitude of the
energy shift depends on the sign of the strain. The linear and non-linear deformation potentials
were determined to be D1=−2.50±0.05 eV and D2=−15.0±0.5 eV, respectively. The nonlinearity
of the energy shift is also reflected in the observed spectral broadening of the emission
peak as a function of the locally induced strain, which decreases with increasing strain on the compressive
side and increases on the tensile side
