Conductivity mechanisms and breakdown of NbO capacitors

článek ve sborníku ve WoS nebo Scopus

angličtina

Niobium Oxide (NbO) capacitor, has already found its place in the market as a cost effective and reliable non-burning component. The study of conductivity mechanisms has been done to prove its good stability, reliability and non-burning performance. Set of electrical measurements as VA characteristics in forward and reverse mode, voltage and frequency characteristics of capacitance, temperature or time dependence of basic parameters together with measurements of basic physical parameters enabled to propose the theoretical model of NbO - Nb2O5 - MnO2 system. A physical model of a solid niobium oxide capacitor based on metal-insulator-semiconductor (MIS) structure is given. The MIS structure consists from metallic niobium oxide, insulating layer made from Nb2O5 and semiconductor - MnO2. The current transport in normal and reverse mode is determined by work function of niobium oxide, Nb2O5, MnO2 and band bending in interface between Nb2O5 and MnO2. The work function difference between niobium oxide and MnO2 (about 1.5 eV) causes two regions of reverse current VA characteristic. Localised energy states are responsible for Poole-Frenkel conductivity mechanism and creation of depletion layer in reverse operation mode. NbO capacitor shows conductivity mechanism similar to tantalum capacitor, but furthermore an unique mechanism appears after dielectric breakdown. It causes a high resistance failure mode of NbO capacitor and limits the current bellow the capacitors thermal runaway point, which prevents capacitor's burning, whereas filtering characteristics remain unchanged.

Capacitors, NbO, breakdown

ŠIKULA, J., HLÁVKA, J., SEDLÁKOVÁ, V., GRMELA, L.

2004

1. 1. 2004

ECA

U.S.A.

0887-7491

Capacitor and Resistor Technology

2004

24

Spojené státy americké

141

146

6