Figure 3
From: Photoinduced oxygen release and persistent photoconductivity in ZnO nanowires
Photoconductivity at three UV intensities in vacuum. Same bias voltage and UV wavelength as in Figure 2. The steady-state currents have not been reached after about 5 h. The wire is kept in vacuum until air is let in after about 12 h (marked by a vertical arrow). The current at t = 0 is higher than that in Figures 1 and 2 because the UV was turned on before the dark current had reached its minimum.