Cryogenic thermal stresses induced in superconducting TiN

Thin film superconductors used for quantum computing applications require cryogenic operating temperatures. Researchers growing superconducting TiN often use room temperature stress as an optimization metric for film quality. During cryogenic use, the mismatch in coefficients of thermal expansion between the TiN film and Si substrate can lead to very large stresses in the film and perhaps plastic deformation.

Measurements of the thermally induced curvature of MBE grown TiN on Si (001) as a function of temperature down to 15 K show compressive and tensile stresses with values exceeding 10 GPa. Experiments monitor thermal cycling hysteresis of the stressed state and survey the possible onset of plastic deformation. Results are interpreted using linear elastic/plastic theory to extract thermally dependent properties of TiN.