title: Two omega method for active thermocouple microscopy.
abstract: We present a contribution to a new mode of scanning thermal microscopy (SThM) based on the use of thermoelectric junction operating in ac active mode. This is the first alternative to 3omega operating mode of a resistive SThM probe for measuring thermophysical parameters of materials at micro- and nanoscale. Whereas a current at omega frequency generates by Joule effect a 2omega thermal oscillation along the wires, the junction thermoelectric voltage can be measured by means of a differential bridge scheme associated to a lock-in amplifier. A thermal model is presented that confirms measurements performed in different situations with different wire probes. Values of thermal contact conductance of different materials have been extracted and a comparison has been performed between this technique and the resistive 3omega mode.
authors.affiliation: Institut FEMTO-ST (CNRS UMR 6174), 32 avenue de l'Observatoire, 25030 Besancon Cedex, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Thiery
authors.forename: Eric
authors.initials: E
authors.lastname: Gavignet
authors.forename: Bernard
authors.initials: B
authors.lastname: Cretin