Tuning of Tungsten Thin Film Superconducting Transition Temperature for Fabrication of Photon Number Resolving Detectors

Published

June 1, 2005

Author(s)

Adriana Lita, Danna Rosenberg, Sae Woo Nam, Aaron J. Miller, Davor Balzar, L. M. Kaatz, R. E. Schwall

Abstract

Tungsten thin films can form in one of two crystal structures: alpha (bcc), with a superconducting transition temperature (T_c) of 15 mK, and beta (A15), with a T_c between 1 and 4 K. Films with intermediate T_cs are composed of both alpha and beta phases. We have investigated how to tune the film T_c in order to obtain certain values (T_c100mK) suitable for fabrication of photon number resolving transition-edge sensor (TES) and arrays of TES detectors for astronomical and quantum information applications. Variation of deposition conditions, and also the choice of the underlayer/coating for equal deposition conditions, affect the T_cs of the tungsten films. We have used x-ray diffraction to determine the structure of tungsten thin films and film stress. The results indicates the the film stress state depends on the underlying substrate and coating. To understand the variation of T_c values and to allow precise tuning of these values, we have investigated substrates and coatings for tungsten film multilayer stacks and determined tungsten film stress by X-ray diffraction at both room temperature and 8 K.

Citation

IEEE Transactions on Applied Superconductivity

Volume

15

Issue

2

Pub Type

Journals

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Keywords

materials processing, stress, superconducting films, x-ray measurements.

Citation

Lita, A. , Rosenberg, D. , Nam, S. , Miller, A. , Balzar, D. , Kaatz, L. and Schwall, R. (2005), Tuning of Tungsten Thin Film Superconducting Transition Temperature for Fabrication of Photon Number Resolving Detectors, IEEE Transactions on Applied Superconductivity, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=31827 (Accessed October 13, 2025)