Open Access Nano Express

Charge transport mechanisms and memory effects in amorphous TaN x thin films

Nikolaos Spyropoulos-Antonakakis1, Evangelia Sarantopoulou1*, Goran Drazic2, Zoe Kollia1, Dimitrios Christofilos3, Gerasimos Kourouklis3, Dimitrios Palles1 and Alkiviadis Constantinos Cefalas1

Author Affiliations

1 National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, 48 Vassileos Constantinou Avenue, Athens 11635, Greece

2 Laboratory for materials electrochemistry, National Institute of Chemistry, Hajdrihova 19, Ljubljana 1000, Slovenia

3 Physics Division, School of Technology, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece

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Nanoscale Research Letters 2013, 8:432  doi:10.1186/1556-276X-8-432

Published: 17 October 2013

Abstract

Amorphous semiconducting materials have unique electrical properties that may be beneficial in nanoelectronics, such as low leakage current, charge memory effects, and hysteresis functionality. However, electrical characteristics between different or neighboring regions in the same amorphous nanostructure may differ greatly. In this work, the bulk and surface local charge carrier transport properties of a-TaNx amorphous thin films deposited in two different substrates are investigated by conductive atomic force microscopy. The nitride films are grown either on Au (100) or Si [100] substrates by pulsed laser deposition at 157 nm in nitrogen environment. For the a-TaNx films deposited on Au, it is found that they display a negligible leakage current until a high bias voltage is reached. On the contrary, a much lower threshold voltage for the leakage current and a lower total resistance is observed for the a-TaNx film deposited on the Si substrate. Furthermore, I-V characteristics of the a-TaNx film deposited on Au show significant hysteresis effects for both polarities of bias voltage, while for the film deposited on Si hysteresis, effects appear only for positive bias voltage, suggesting that with the usage of the appropriate substrate, the a-TaNx nanodomains may have potential use as charge memory devices.

Keywords:
Nitrides; TaNx thin films; Amorphous semiconductors; Nanoelectronics; Memory effects; Conductive-AFM