High-temperature phase transitions in SrHfO₃: A Raman scattering study

¹ Centre of Material Sciences, Institute of Interdisciplinary Studies (IIDS), University of Allahabad Allahabad 221002, India
² Division of Materials Science, University of Tsukuba - Ibaraki 305-8573, Japan
³ Department of Physics and Institute of Functional Nano Materials, University of Puerto Rico San Juan, PR 00931-3343, USA
⁴ Department of Physics, Cavendish Laboratory - J. J. Thomson Avenue, Cambridge CB3 0HE, UK

^(a) mksingh100@yahoo.com
^(b) jfs32@cam.ac.uk

Received: 25 April 2014
Accepted: 28 June 2014

Abstract

SrHfO₃ (SHO) is probably the leading gate oxide for the Si chip industry. The material is processed at and annealed at high temperature . Unfortunately there are two phase transitions in SrHfO₃ in this temperature range, which can affect the quality of the final films processed, especially their channel mobility in SHO-based n-FET. To clarify these transitions and their impact on SrHfO₃ processing, we report the temperature dependence of soft phonon modes by Raman spectroscopy. The 1023 K transition is found to be displacive (no disorder) and nearly second order. Significant effects are also seen in the orthorhombic-orthorhombic transition at 670 K.