Influence of the band bending on the photoconductivity of Li-doped ZnO microwires

Combining photoconductivity and photoluminescence measurements we have studied the band bending behavior with the Li-doping content in ZnO microwires. Our results reveal the presence of in-gap acceptor levels with energies ranging from 100 meV to 600 meV above valence band maximum. We have found that the band bending plays an important role in the photoconductivity modifying the life time of the photocarriers and enhancing the near band edge peak of photoluminescence in Li-doped samples. Using a simple model we have evaluated the influence of the band-bending on the relaxation time for the photoconductivity.