Amorphous Y–Ba–Cu–O oxide thin films: Structural, electrical and dielectric properties correlated with uncooled infrared pyroelectric detection performances

• Published in: Thin solid films Vol. 553; pp. 104 - 108
• Main Authors: Dégardin, Annick F., Galiano, Xavier, Gensbittel, Aurélie, Dubrunfaut, Olivier, Jagtap, Vishal S., Kreisler, Alain J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 28.02.2014; Elsevier
• Subjects: Amorphous semiconductor; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Conductivity; Correlated barrier hopping model; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Dielectric relaxation; Electrical properties of specific thin films; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Low noise fast detection; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Schottky contact; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Uncooled pyroelectric detector; YBCO; Low noise fast detection; Schottky contact; Correlated barrier hopping model; Conductivity; YBCO; Amorphous semiconductor; Dielectric relaxation; Uncooled pyroelectric detector; Temperature dependence; Frequency dependence; Electrical conductivity; Electrical properties; Lithography; Amorphous semiconductors; Dielectric properties; Infrared detection; Charge transport; Thin films; Detectors; Sputter deposition; Microstructure; Activation energy
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2013.10.103

Semiconducting amorphous YBa2Cu3O6+x (x<0.5, a-YBCO) films of 140nm to 880nm thickness were deposited by direct current (DC) hollow cathode sputtering at low temperature (≈150°C). The film microstructure was typically granular. Dielectric measurements from 100Hz to 2MHz were performed in the 300–430K range to characterize the charge transport behavior. Alternating current conductivity values were extracted and the frequency dependence revealed a relaxation mechanism, which strength increased with temperature according to an Arrhenius law. The activation energy values matched those deduced from the temperature dependence of DC conductivity. The observed relaxation was in line with the hopping charge transport mechanism. A tri-layer device (metal/a-YBCO/metal on Si/SiO2 substrate) was processed using standard lithography. DC electrical tests confirmed the Schottky nature of the metal/a-YBCO contact. The optical response at 850nm wavelength exhibited a high-pass behavior (maximum response at 100kHz/1.6μs time constant). The device current noise spectrum – of “blue” character – was investigated and discussed, in line with the frequency behavior of a-YBCO conductivity. A large signal/noise ratio was obtained, resulting in detectivity D*>109cm·Hz1/2·W−1 in the 7kHz to 100kHz frequency range. These results are testifying for the very good performance of a-YBCO as room temperature pyroelectric sensing material. •Semiconducting YBCO films for uncooled infrared pyroelectric detectors are studied.•AC electrical conductivity is correlated with film amorphous microstructure.•Results are interpreted in terms of a correlated barrier hopping model.•An a-YBCO tri-layer device exhibits a low noise and fast pyroelectric response.•Device noise spectrum is in line with the conductivity frequency dependence.