Photon induced Schottky barrier effects in inverse-extraordinary optoconductance structures

We expand upon our previous work and characterize the photo-dependence of the effective Schottky barrier in EOC and I-EOC heterostructures by measuring the open circuit voltage and the change in the reverse bias resistance. Under full illumination by a 5 mW, 632.8 nm HeNe laser, the barrier is effectively eliminated and the Ti-GaAs interface becomes Ohmic. The reverse bias resistance changes by a factor of 209 over an illumination intensity change of 10–5:1. While this work illustrates the behavior of the Schottky interface upon illumination, it also demonstrates the effectiveness of the four-point, van der Pauw measurement fundamental to EOC/I-EOC phenomena at monitoring changes in the active region of the mesa. The resistance is largely unaffected by the photovoltaic, DC offset of the surrounding leads, as indicated by the radial symmetry of 2-D resistance maps obtained by rastering the laser across EOC/IEOC devices