SnO2, ZnO and related polycrystalline compound semiconductors : An overview and review on the voltage-dependent resistance (non-ohmic) feature

• Published in: Journal of the European Ceramic Society Vol. 28; no. 3; pp. 505 - 529
• Main Authors: BUENO, Paulo R, VARELA, José A, LONGO, Elson
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier 2008
• Subjects: Applied sciences; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Exact sciences and technology; Performance evaluation; Varistors; Voltage dependence; Electronic properties; Perovskite type compound; Polycrystal; Review; Varistance; Grain boundary; Tin oxide; Zinc oxide; SnO2; ZnO; Microstructure; Ceramic materials; Resistor; Comparative study; Damaging
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2007.06.011

The history of SnO2-based voltage-dependent resistors is reviewed, and the main characteristics of these polycrystalline semiconductor systems are discussed, including a direct comparison with traditional ZnO-based voltage-dependent resistor systems to establish the differences and similarities, giving details of the basic physical principles involved with the non-ohmic properties in both polycrystalline systems. The main difficulties involved in processing SnO2- and ZnO-based non-ohmic systems are described, with an evaluation of the contribution of the dopants to the electronic properties and to the final microstructure and consequently to the non-ohmic behaviour of the system. The main focus is on the SnO2-based varistor systems, but the basic physical principles described are universally useful in the context of dense polycrystalline devices. New perspectives for applications, commercialisation and degradation studies involving SnO2-based polycrystalline non-ohmic systems are outlined, including recent technological developments. A brief section is dedicated to the presentation and discussions about other emerging non-ohmic polycrystalline ceramic devices (particularly based on perovskite ceramics) which must be studied in depth in the years to come, because some of these systems present combined high dielectric and non-ohmic properties. 164 refs.