Photocurrents in SnO₂films due to desorption of oxygen

Abstract

Abslmd. Large changes of conductivity QCCUT in annealed pyrolytic SnOz films when irradiated with ulvaviolet radiation under ambient conditions. We have found that this effect is due to chemisorption-photodorption of oxygen following an Elovich-type kinetics, and hat chemisorption pmceeds by the transfer of electrons through a potential barrier.

Photoconductivity in In2O3 nanoscale thin films: Interrelation with chemisorbed-type conductometric response towards oxygen

“…One can note that similar behavior of a transient photoresponse possessing two different parts was observed in [18]. However, in our case, the transient process did not obey the Elovich relation, being usually observed on metal oxides at room temperature (see, for example, in [1]). It is important to note that transient curves of PC are described by an equation similar to ones used to explain transient conductivity curves during gas sensing effects [29,30].…”

“…Difficulties in describing the operation mechanism have arisen first of all due to a lack of essential information about surface electronic levels responsible for surface conductivity modulation under an environment change. In many experiments related to transparent conductive metal oxides (TCO), it was shown that there is a principal contribution from adsorbed oxygen, namely through it's desorption [1][2][3][4], in the photoconductivity (PC) properties of nanoscale metal oxides. However, we have to note that all indicated experiments were carried out at or below room temperature (RT), i.e., under conditions during which TCO photoconductivity, especially in the ultra violet (UV) range, was irreversible in many cases.…”

Photoluminescence properties of a hollandite compound K2Ga2Sn6O16

“…The increase in PL intensity of the SnO 2 powder can be explained in the same way as the increase in PL intensity of the TiO 2 powder was explained in the previous paragraph. This explanation is consistent with the fact that the photodesorption of O 2 occurs on the SnO 2 surface [19]. In contrast, the time-courses of the PL intensities of the KGSO powder (Fig.…”

Modified TiO2coatings for cathodic protection applications

“…Generally, during its synthesis, when SnO 2 is heattreated in an aerated atmosphere, i.e. air or pure O 2 at temperatures greater than 640 8C, a chemisorption of O 2 on SnO 2 takes place leading to an increase in its electrical resistance [16]. There is an electron transfer that is taking place in this case, from the conduction band of SnO 2 to an acceptor level introduced by the chemisorbed atoms.…”

“…In a deoxygenated condition, the second reaction is thermodynamically favored according to which, a photodesorption takes place as a result of which, the free electrons that are available, increase in number on prolonged exposure to illumination [16,17].…”