Spatial distribution of oxygen vacancies in Cr-doped SrTiO3 during an electric-field-driven insulator-to-metal transition

Abstract

Spatially resolved x-ray fluorescence maps are presented that show the introduction and the evolution of oxygen vacancies in chromium-doped strontium titanate during an electric-field-driven insulator-to-metal transition. The vacancies are introduced at the anode and diffuse through the crystal toward the cathode. The spatial distribution of vacancies is explained by a model describing the electrical breakdown as a percolation process. Strong differences in the vacancy distribution were found when the transition took place in air and in a hydrogen-enriched atmosphere. In air, the vacancies disappeared from the surface, whereas in the reducing hydrogen atmosphere, they remained at the surface.

Modulation of resistance switching in Au/Nb:SrTiO3 Schottky junctions by ambient oxygen

“…1 Experiments on metal-insulatormetal cells using binary oxide thin films and perovskite-type single-crystal oxides (e.g., TiO 2 , ZnO, NiO, and SrTiO 3 ) recently demonstrated a strong influence of the ambient gases on RS. [2][3][4][5][6][7][8][9] In particular, it was shown that environmental oxygen affects both the electroforming process and the cell functionality by surface adsorption and chemical oxidation. [3][4][5][6][7][8][9] The generality of this picture suggests a prominent role of ambient oxygen for other oxide structures, dominated by different interfacial RS mechanisms.…”

Formation and Movement of Cationic Defects During Forming and Resistive Switching in SrTiO3 Thin Film Devices

“…[ 14 ] In addition to the ionic mobilities, an indication of the oxygen vacancy-related phenomenon in STO single crystals and thin fi lms has been provided by a variety of spectroscopic investigations. [ 15,16 ] However, the fi lamentary resistive switching is often accompanied by very high local temperatures. [ 17 ] In particular, during the initial electroforming step, the temperatures may come close to the melting temperature of the oxide.…”

Spectromicroscopy of tantalum oxide memristors

“…These motivations have driven significant recent advances in device development and materials research. [7][8][9][10][11][12] One promising material system is tantalum oxide, 13,14 which has demonstrated over 10 9 cycles of write/erase endurance, relatively low power operation, and no required electroforming step. As yet, there is little understanding of the microscopic switching mechanism, including, for example, the presence and material composition of any conductive channels.…”