Premium
Towards Understanding the Cross‐Sensitivity of In 2 O 3 Based Ozone Sensors: Effects of O 3 , O 2 and H 2 O Adsorption at In 2 O 3 (111) Surfaces
Author(s) -
Berthold Theresa,
Katzer Simeon,
Rombach Julius,
Krischok Stefan,
Bierwagen Oliver,
Himmerlich Marcel
Publication year - 2018
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201700324
Subject(s) - ozone , band bending , x ray photoelectron spectroscopy , adsorption , chemistry , analytical chemistry (journal) , oxidizing agent , oxygen , work function , molecule , annealing (glass) , materials science , chemical engineering , electrode , environmental chemistry , optoelectronics , organic chemistry , engineering , composite material
The interaction of ozone, oxygen, and water molecules with the (111) surface of indium oxide grown by plasma‐assisted molecular beam epitaxy is investigated. In order to characterize the adsorption and charge transfer mechanisms taking place at ozone‐sensitive In 2 O 3 films and to determine the effect of humidity, we study the chemical and electronic surface properties using photoelectron spectroscopy. Clean surfaces are prepared by vacuum annealing and subsequently exposed to O 3 , O 2 , or H 2 O in serial adsorption sequences. After ozone and oxygen interaction, the same adsorbate species are detected and both molecules reduce the surface electron density, resulting in a decrease of film conductance. However, the quantitative changes of adsorbate coverage, band bending, surface electron concentration, and work function indicate a much higher reactivity of the surface with ozone. In contrast, if the surface is exposed to water, the resulting adsorbates have a different spectroscopic signature and do not significantly alter surface band bending and electron concentration. The effects of ozone/oxygen interaction are weakened if the surface was pre‐exposed to water. These results indicate that water adsorbates occupy surface sites that are consequently not available for ozone interaction and that humidity influences the device sensitivity but not its selectivity toward oxidizing gases.