Experimental setup combining in situ hard X-ray photoelectron spectroscopy and real-time surface X-ray diffraction for characterizing atomic and electronic structure evolution during complex oxide heterostructure growth

Gyula Eres; C M Rouleau; Q Lu; Z Zhang; E Benda; Ho Nyung Lee; J Z Tischler; D D Fong

doi:10.1063/1.5116135

Experimental setup combining in situ hard X-ray photoelectron spectroscopy and real-time surface X-ray diffraction for characterizing atomic and electronic structure evolution during complex oxide heterostructure growth

Rev Sci Instrum. 2019 Sep;90(9):093902. doi: 10.1063/1.5116135.

Authors

Gyula Eres¹, C M Rouleau², Q Lu¹, Z Zhang³, E Benda³, Ho Nyung Lee¹, J Z Tischler³, D D Fong⁴

Affiliations

¹ Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
² Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
³ X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA.
⁴ Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA.

PMID: 31575256
DOI: 10.1063/1.5116135

Abstract

We describe the next-generation system for in situ characterization of a complex oxide thin film and heterostructure growth by pulsed laser deposition (PLD) using synchrotron hard X-rays. The system consists of a PLD chamber mounted on a diffractometer allowing both real-time surface X-ray diffraction (SXRD) and in situ hard X-ray photoelectron spectroscopy (HAXPES). HAXPES is performed in the incident X-ray energy range from 4 to 12 keV using a Scienta EW4000 electron energy analyzer mounted on the PLD chamber fixed parallel with the surface normal. In addition to the standard application mode of HAXPES for disentangling surface from bulk properties, the increased penetration depth of high energy photoelectrons is used for investigation of the electronic structure changes through thin films grown deliberately as variable thickness capping layers. Such heterostructures represent model systems for investigating a variety of critical thickness and dead layer phenomena observed at complex oxide interfaces. In this new mode of operation, in situ HAXPES is used to determine the electronic structure associated with unique structural features identified by real-time SXRD during thin film growth. The system is configured for using both laboratory excitation sources off-line and on-line operation at beamline 33-ID-D at the Advanced Photon Source. We illustrate the performance of the system by preliminary scattering and spectroscopic data on oxygen vacancy ordering induced perovskite-to-brownmillerite reversible phase transformation in La_2/3Sr_1/3MnO₃ films capped with oxygen deficient SrTiO_3-δ (100) layers of varying thickness.