Influence of the metastable state (V 0++) on the electronic properties of SnO2nanowires under the influence of light

In general, the properties of oxide materials are directly related to the formation of defects in their structure. In this work, a correlation between the intrinsic defects of SnO2 nanowires with their optoelectronic and transport properties and the influence of illumination was traced. Photoluminescence experiments revealed that SnO2 nanowires are characterized by three emission centers related to oxygen vacancies, V 0 + (red), (V 0 +) iso (yellow/orange), and V 0 + + (green), the latter being active only below 100 K. This metastable defect was associated with the anomalous behavior observed in the temperature-dependent resistivity curves of ohmic single-nanowire devices under the influence of light. Two activation energies for a single nanowire in different temperature regions (T < 100 K and T > 100 K) were identified by photocurrent measurements. The activation energy for T < 100 K (7 meV) is consistent with the small value obtained in the photoluminescence experiments for the green-emitting center (3 meV). For the high-temperature region (T > 100 K), a higher activation energy value (220 meV) was observed.