Growth of EuO Thin Films by Molecular-Beam Epitaxy

Open Access
Ulbricht, Ross
Graduate Program:
Materials Science and Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
Committee Members:
  • Darrell G Schlom, Thesis Advisor
  • epitaxy
  • semiconductor
  • magnetic
  • thin film
  • crystal
  • MBE
  • EuO
  • XRD
  • rheed
The highly spin polarized ferromagnetic semiconductor, EuO is being examined as a candidate material for spintronics applications. Its development in this role has been stifled, however, by difficulties in synthesizing high quality, epitaxial thin-films. Using molecular-beam epitaxy, these difficulties have been overcome and the adsorption-controlled growth of expitaxial EuO films on single crystalline (110) YAlO3 substrates has been demonstrated. The optimal substrate temperature and oxygen background partial pressure for the growth of high quality EuO have been determined to be 590 °C and 1×10-9 torr, respectively. Four-circle x-ray diffraction (XRD) reveals phase-pure, epitaxial, (001)-oriented films with rocking curve full width at half maxima as narrow as 34 arc seconds (0.0097°). Off-axis XRD analysis shows that the unit cell of the EuO film is rotated by 45° with respect to the surface net of the (110) YAlO3 substrate, inducing an ~2%, in-plane tensile strain in commensurate films due to lattice mismatch. The critical thickness for the onset of relaxation of (001) EuO on (110) YAlO3 was determined from XRD measurements in combination with Rutherford backscattering spectrometry (RBS) to be 382±25 Å. A saturation magnetization of 6.96±0.07 µB/Eu, a value close to the theoretical limit of 7 µB/Eu, was measured on these epitaxial EuO films using a superconducting quantum interference device (SQUID) magnetometer.