Deep energy levels and photoelectrical properties of thin cuprous oxide films

Thin films of cuprous oxide have been electrodeposited on molybdenum substrates. Some preliminary photoelectrical properties of two devices with semitransparent aluminum and gold top-electrodes have been measured. The device with a gold top-electrode exhibits a weak photovoltaic effect and a space charge limited current conduction mechanism in dark. The other device which had been annealed before the deposition of the aluminum top-electrode, exhibits a three-fold increase in resistivity and a marked difference in its temperature dependence of conductivity. From the temperature dependence of conductivity, two activation energies of 0.09 and 0.87 eV could be measured compared to 0.11 and 0.26 eV for the device with a gold electrode. Photoinduced current transient spectroscopy with a novel approach to the post-capture data analysis (additive double gate analysis) has been used in detection and the measurements of the parameters of several deep energy levels. These levels have activation energies in the range of 0.12 to 0.63 eV and capture cross-sections in the range of 10(-22) to 10(-12) cm(2). Using the role of the sample bias polarity on the identification of the type of the traps, one electron trap (surface state) and one hole trap (bulk state) could be identified among the five detected deep levels.