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Characterization and In-situ Monitoring of Sub-stoichiometric Adjustable T_c Titanium Nitride Growth

Vissers, Michael R. and Gao, Jiansong and Kline, Jeffrey S. and Sandberg, Martin and Weides, Martin P. and Wisbey, David S. and Pappas, David P. (2012) Characterization and In-situ Monitoring of Sub-stoichiometric Adjustable T_c Titanium Nitride Growth. . (Unpublished) http://resolver.caltech.edu/CaltechAUTHORS:20160310-155827664

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Abstract

The structural and electrical properties of Ti-N films deposited by reactive sputtering depend on their growth parameters, in particular the Ar:N_2 gas ratio. We show that the nitrogen percentage changes the crystallographic phase of the film progressively from pure α-Ti, through an α-Ti phase with interstitial nitrogen, to stoichiometric Ti_2N, and through a substoichiometric TiN_X to stoichiometric TiN. These changes also affect the superconducting transition temperature, T_c, allowing, the superconducting properties to be tailored for specific applications. After decreasing from a T_c of 0.4 K for pure Ti down to below 50 mK at the Ti_2N point, the T_c then increases rapidly up to nearly 5 K over a narrow range of nitrogen incorporation. This very sharp increase of T_c makes it difficult to control the properties of the film from wafer-to-wafer as well as across a given wafer to within acceptable margins for device fabrication. Here we show that the nitrogen composition and hence the superconductive properties are related to, and can be determined by, spectroscopic ellipsometry. Therefore, this technique may be used for process control and wafer screening prior to investing time in processing devices.


Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription
http://arxiv.org/abs/1209.4626arXivDiscussion Paper
Additional Information:This work is a contribution of U.S. Government, not subject to copyright. We acknowledge support for this work from DARPA, the Keck Institute for Space Studies, the NIST Quantum Initiative, and NASA under Contract No. NNH11AR83I. The authors thank Jonas Zmuidzinas and Henry Leduc for helpful discussions and insights. This work is a contribution of U.S. Government, not subject to copyright. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressly or implied, of the U.S. government.
Group:Keck Institute for Space Studies
Funders:
Funding AgencyGrant Number
Defense Advanced Research Projects Agency (DARPA)UNSPECIFIED
Keck Institute for Space Studies (KISS)UNSPECIFIED
National Institute of Standards and Technology (NIST)UNSPECIFIED
NASANNH11AR83I
DOI:10.26206/S8YC-2364
Record Number:10.1016/j.tsf.2013.07.046
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20160310-155827664
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:65279
Collection:CaltechAUTHORS
Deposited By: Colette Connor
Deposited On:14 Mar 2016 18:59
Last Modified:21 Mar 2019 21:15

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