Influence of dielectric relaxation on thermal electrical characteristics of SrTiO3 thin films with Pt electrodes

Abstract

In this presentation we report on the influence of dielectric relaxation on the thermal leakage characteristics of Pt/SrTiO3/Pt thin film structures. We study the influence of temperature and time-dependent leakage currents on recently reported phenomena such as anomalous positive temperature coefficient of resistivity and resistive switching behavior. SrTiO3 was chosen as a model thin film because the dielectric relaxation is not influenced by ferroelectric polarization, as, for example, for (Ba,Sr)TiO3 thin films. We have measured the leakage currents of sputtered, strongly (110) textured SrTiO3 thin films with Pt top and bottom electrodes as a function of time, film thickness, bias field and temperature. We show that apparent dielectric relaxation times decrease with film thickness and increasing temperature and ranged between 1 Ç¿Ï 100 seconds. We show that hysteresis in the I¿V characteristics is strongly correlated with the non-steady state characteristics of the electrical characteristics. The sign of the applied bias field influenced both dielectric relaxation times and hysteresis, reflecting different trap state distributions near bottom and top contacts and/or different barrier heights. Measurements of the leakage currents under applied bias fields as a function of temperature showed distinctive peak was observed around 260K that could be correlated with non-steady state current. We show that for thick films results can be interpreted in terms of trapping/detrapping in the ! depletion region of the blocking contacts. Finally we report on the influence of oxygen vacancies on the hysteresis of the I¿V characteristics and non-steady state current.