Study of MgO tunnel barriers with conducting atomic force microscopy

The impact of oxygen vacancies on local tunneling properties across rf-sputtered MgO thin films was investigated by optical absorption spectroscopy and conducting atomic force microscopy. Adding O 2 to the Ar plasma during MgO growth alters the oxygen defect populations, leading to improved local tunneling characteristics such as a lower density of current hotspots and a lower tunnel current amplitude. We discuss a defect-based potential landscape across ultrathin MgO barriers.

supporting

confidence: 79%

Control of defect-mediated tunneling barrier heights in ultrathin MgO films

Kim

Choi

Schleicher

et al. 2010

“…However, even if important research has been done regarding the development of magnetic tunnel junctions [6][7][8] and spin filters, 9 very little work has been done in the study and characterization of insulating barriers for the development of Josephson junctions using CAFM. 10 The characteristics of the barrier, e.g., roughness, energy, and the attenuation length of the current, depend on the electronic properties of the electrodes.…”

mentioning

confidence: 99%

Structural and transport characterization of ultra thin Ba0.05Sr0.95TiO3 layers grown over Nb electrodes for the development of Josephson junctions

Sirena

Avilés-Félix

Vera

et al. 2012

A phenomenological approach was used to obtain critical information about the structure and electrical properties of ultra thin Ba0.05Sr0.95TiO3 (BSTO) layers over Nb electrodes. The method allows, in a simple way, to study and to optimize the growth of the barrier in order to improve the performance and application of Josephson junctions. A very good control of the layer thickness with a low roughness was achieved during the deposition process. The BSTO layers present an energy barrier of 0.6 eV and an attenuation length of 0.4 nm, indicating its good insulating properties for the development of Josephson junctions with improved performance.

“…Others have developed scanning-tunneling type measurements to image current density directly in efforts to locate the relevant defects. 3,4 While these methods do pinpoint the locations of anomalous behavior, the extraction of such regions for further study is not straightforward. Recently, Petford-Long and co-workers demonstrated that in situ tunneling experiment can be done in a TEM, on a film crosssection consisting of two ferromagnetic electrodes separated by an insulator.…”

Section: In Situ Tunneling Measurements In a Transmission Electron MImentioning

confidence: 99%

In situ tunneling measurements in a transmission electron microscope on nanomagnetic tunnel junctions

Lau

Morrow

Read

et al. 2010

We showed that a chain of nanomagnetic tunnel junctions (MTJs) devices can be electrically addressed individually, in situ, in a transmission electron microscope, such that transport properties can be in principle, quantitatively correlated with each device’s defects and microstructure. A unique energy barrier was obtained for each device measured. Additionally, in situ tunneling magnetoresistance (TMR) measurements were obtained for a subset of devices. We found that TMR values for our nano-MTJs were generally smaller than TMR in the unpatterned film.