The influence of visible light on transparent zinc tin oxide thin film transistors

The characteristics of transparent zinc tin oxide thin film transistors (TTFTs) upon illumination with visible light are reported. Generally, a reversible decrease of threshold voltage V-th, saturation field effect mobility mu(sat), and an increase of the off current are found. The time scale of the recovery in the dark is governed by the persistent photoconductivity in the semiconductor. Devices with tuned [Zn]:[Sn] ratio show a shift of V-th of less 2 V upon illumination at 5 mW/cm(2) (brightness > 30 000 cd/m(2)) throughout the visible spectrum. These results demonstrate TTFTs which are candidates as pixel drivers in transparent active-matrix organic light emitting diode displays.