P4.3 - Integrated System Scanning Probe Microscope - Quartz Microbalance: in-situ Testing of Surface Potential, Topography and mass of the adsorbed gases.

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings SENSOR 2011
P4 - Gas
V. Popov, R. Pavelko, V. Sevastynov, N. Kuznetsov, N. Kurnaakov - Institute of General and Inorganic Chemistry, Moscow (Russia)
756 - 761


In-situ measurements of electron workfunction together with mass registration of the analyte, adsorbed on the semiconductor surfaces, provide promising tool for better understanding of surface processes related with gas sensor phenomenon. In this study scanning probe microscope (SPM, Solver ProM, NT-MDT, Russia) was used both in contact and Kelvin probe mode to measure surface topography and potential of SnO2 materials deposited on quartz microbalance (QMB, MP3QCM, NT-MDT, Russia).
QMB resonator, being easily replaceable element of the system, can be used as a substrate to deposit layers of polycrystalline materials through various methods, e.g. (AA) CVD, sol-gel technique, atomic layer deposition, Langmuir–Blodgett deposition, flame spray pyrolysis etc. In this study we used drop coating method to deposit following materials from water suspensions: SnO2, SnO2 doped with Pd, and HfO2 with deposited bromocresol purple. The experiment with blank QMB resonator was also performed.
Surface potential as well as sample topography were measured at room temperature in target gas atmosphere. QMB resonator, operating at 15MHz, was used to measure the mass of the adsorbed gases, estimated as a frequency difference between the measurements in air and in the target gas. The measurements were performed in air, 10% NH3, 0.1% H2 and 0.1% CH4 all in air.
Mapping of the surface potential allows one to estimate the effect of the surface morphology on the measured parameter. The dependency of the mass of the adsorbed species on the electron work function was obtained. The principal potentialities of the SPM technique integrated with QMB are shown and tested.