title: In-situ monitoring of the dielectric and electrostrictive properties of anodised thin films for biochip applications.
abstract: Further improving the performance of capacitance-based DNA microsensors will depend on the ability to synthesize simply, at a low cost, thin films of high dielectric permittivity with a well-controlled growth morphology. Anodisation of the valve metals Ti, Zr and Ta is a promising route for preparing such films. In this paper, we propose a new method for following the evolution of the dielectric properties of such anodised metallic oxide thin films in-situ during their growth. The technique relies on measuring the evolution of the electrostatic stress developing in the film. Measurements have been carried out on anodic TiO(2) films grown galvanostatically in HNO(3) at 1 and 3 mA/cm(2) and in H(3)PO(4) at 0.5 mA/cm(2). The dielectric permittivity of the films was observed to decrease during the initial stage of anodisation, characterised by a steady increase of the cell voltage with time. The permittivity then reached a constant value when the oxide entered a second growth regime, characterised by a stabilisation of the cell voltage. The origin of the observed permittivity evolution is interpreted in terms of the evolution of the growth morphology of the films during anodisation.
authors.affiliation: Division of Materials and Process Engineering, Université Catholique de Louvain, Place Sainte-Barbe 2, B-1348 Louvain-la-Neuve, Belgium. proost@imap.ucl.ac.be
authors.forename: J-F
authors.initials: JF
authors.lastname: Vanhumbeeck
authors.forename: J
authors.initials: J
authors.lastname: Proost
mesh_terms: D000497:Alloys / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D004563:Electrochemistry / Q000379:methods*; D007700:Kinetics; D036103:Nanotechnology / Q000379:methods*; D017942:Nitric Acid / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D010756:Phosphoric Acids / Q000737:chemistry; D055672:Static Electricity; D013499:Surface Properties; D013635:Tantalum / Q000737:chemistry; D014025:Titanium / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
chemical_list: D000497:Alloys; D010087:Oxides; D010756:Phosphoric Acids; C009495:titanium dioxide; D017942:Nitric Acid; D013635:Tantalum; D015040:Zirconium; D014025:Titanium; C030242:phosphoric acid; C078151:tantalum oxide; C028541:zirconium oxide