High-Field Conduction in Barium Titanate

TL;DR

This study investigates high-field leakage currents in ultra-thin barium titanate crystals, demonstrating space charge limited conduction with a continuous trap distribution at fields up to 1.3 GV/m, surpassing earlier studies.

Contribution

It provides the first detailed analysis of SCLC in BaTiO3 at extremely high electric fields, extending the understanding of conduction mechanisms in ferroelectric materials.

Findings

Leakage current governed by SCLC with a continuous trap distribution.

High-field conduction behavior differs from variable range hopping models.

Comparable SCLC behavior observed in ceramic multilayer capacitors.

Abstract

We present current-voltage studies of very thin (ca. 77 nm) barium titanate single crystals up to 1.3 GV/m applied field. These show that the mechanism of leakage current at high fields is that of space charge limited conduction (SCLC) in a regime with a continuous distribution of traps, according to the original model of Rose [Phys. Rev. 97, 1537 (1955)]. This study represents a factor of x5 in field compared with the early studies of BaTiO3 conduction [A. Branwood et al., Proc. Phys. Soc. London 79, 1161 (1962)]. Comparison is also given with ceramic multilayer barium titanate capacitors, which show similar SCLC behaviour. The data are shown to be completely incompatible with variable range hopping [B. I. Shklovskii, Sov. Phys. Semicond. 6, 1964 (1973)], despite the recent report of such mechanism in SrTiO3 films [D. Fuchs, M. Adam, and R. Schneider, J. Phys. IV France 11, 71 (2001)].