Effect of strong illumination on current-voltage characteristics of Au/Si, Al/Si and Sn/Si Schottky barriers with native oxide layer

Light induced general degradation in the dark I-V characteristics of Au/Si, Al/Si and Sn/Si junctions at low temperature and at room temperature. Illumination caused changes in the interface and bulk properties of the investigated junctions, all of them prepared under identical conditions. Their barrier heights, phi(B) change with increasing illumination time. The largest rate of degradation in phi(B) upon exposure to light was observed for an Sn/Si junction (lowest phi(B)), whereas the smallest change occurred with an Au/Si junction (highest phi(B)). At low temperature, upon turning off the light, the photogenerated current of the Sn/Si sample exhibited faster recovery in reaching the initial dark current (at t(ill) = 0) than the Al/Si junction; for the less reactive Au/Si sample, the presence of the oxide layer reduced the leakage current and subsequently delayed recovery of the measured photocurrent.