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Role of structural and phase change of doped metal oxide SnO2 and In2O3 in formation of gas sensing properties of chemiresistive sensors

Author: Boris Iulia
Degree:doctor of Physics
Speciality: 01.04.10 - Semiconductors physics and engineering
Scientific adviser: Vladimir Brînzari
doctor, associate professor (docent)
Institution: Moldova State University


The thesis was presented on the 21 December, 2015
Approved by NCAA on the 25 February, 2016


Adobe PDF document0.72 Mb / in romanian
Adobe PDF document0.74 Mb / in russian


CZU 621.315.592.3

Adobe PDF document 2.55 Mb / in russian
129 pages


In2O3, SnO2, sol-gel, spray pyrolysis, doping, gas sensing properties, nanostructure changes


The thesis consists of Introduction, 4 Chapters, General conclusions and recommendations, 170 References, 129 Pages, 55 Figures, 3 Tables. The results presented in the thesis are published in 44 scientific works.

Domain of study: gas sensors.

Goal and objectives: comprehensive and comparative research of In2O3- and SnO2-based binary oxides doped by additives of different type and valence (from metals to non-metals) and establishment of the additive role on their gas sensing properties on an example of sol-gel and thin-film technologies.

Scientific novelty and originality: for the first time it was carried out the comprehensive and comparative study of In2O3-based one-electrode gas sensors prototypes for the wide range of doping additives; it was found the effect of mutual nanoclusters formation of both base oxide and additive oxides for SnO2 doped by Co, Cu, Fe, Ni at doping levels exceeding the limit volume solubility.

Important scientific problem solved: it was demonstrated the possibility of gas sensing properties control for metal oxides based on In2O3 ceramics and SnO2 thin films through their doping by additives of different type and it was established the structural and the sensor activity of these additives.

Theoretical importance: it was clarified contribution of adsorption and electronic mechanisms to gas sensing improvement or suppression at doping, their connection with the transitions from the volume solubility to the formation of a separate phase of the additive oxides both for In2O3 and SnO2.

Practical significance: the prototypes of one-electrode and thin-film sensors based on In2O3 and SnO2 with improved operational characteristics, such as increased gas sensitivity (In2O3: Ga, P, Cu, Zn), (SnO2: Cu, Co), increased selectivity (In2O3: Cu, P, Mn), increased stability (In2O3: Ga, Al, Zn, Fe), low response recovery times, low sensitivity to humidity(In2O3: Ga, Al) were proposed.