The spectral distribution of photoconductivity in Ag2O was measured on samples prepared in three different ways. The photoresponse was found to depend on the mode of preparation of samples and on previous light exposure. Samples prepared by pressing Ag2O powder against a cellulose backing showed a photoconductive peak around 0.9 μm, while thin Ag2O layers prepared by cathodic sputtering of silver in an oxygen atmosphere behaved like the ideal photoconductors: flat response in the visible and exponential decrease from 0.8 μm to longer wavelengths. Some infra‐red optical absorption and electrical conductivity measurements were also made. The results are compared to the behaviour of Cu2O, silver oxide's only structural analogue.
Hall-effect and electrical conductivity measurements were performed on Cu2O single crystals both before and after heating the samples in vacuo at temperatures ranging from 200 °C to 800 °C. Both the absolute values of the mobility and the conductivity, as well as their temperature dependence, were found to be strongly altered by the heating process. Room-temperature conductivities usually dropped from 10−6 ohm−1 cm−1 to 10−8 ohm−1 cm−1, while the mobility increased from about 30 to 100 cm2 V−1 sec−1 after heating to 300 °C. At the same time, the activation energies for the conductivity increased and a region of exponential temperature dependence for the mobility showed up. Vacuum heating above 800 °C again changed the sample characteristics quite drastically and appeared to stabilize them with respect to their environment with different atmospheres. Reproducibility for a given sample and from sample to sample could be obtained only after heating the samples in vacuo. The results are compared with previous investigations, and it is suggested that different surface conditions or thermal histories could account for the wide variety of data found in the literature.
A complex Raman spectrum of Cu2O has been measured using the Kr laser line at 6471 Å, and comparison with the infrared absorption spectrum is made. An F2g Raman active phonon, postulated from symmetry considerations and infrared absorption measurements to lie at either 606 or 181 cm−1, could not be observed. Strong lines are, however, observed at 220, 204, and 192 cm−1.
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