AVS 53rd International Symposium
    Electronic Materials and Processing Thursday Sessions
       Session EM-ThP

Paper EM-ThP21
Molecular Beam Epitaxy of YMnO@sub 3@ on c-plane GaN

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: Electronic Materials and Processing Poster Session
Presenter: C.B. Keenan, West Virginia University
Authors: C.B. Keenan, West Virginia University
T. Liu, West Virginia University
K. Lee, West Virginia University
R.P. Tompkins, West Virginia University
E.D. Schires, West Virginia University
Y. Chye, West Virginia University
D. Lederman, West Virginia University
T.H. Myers, West Virginia University
Correspondent: Click to Email
Ferroelectric oxide thin films on semiconductors have attracted attention for their potential applications in nonvolatile memory, piezoelectric, and microwave devices. Interest is now emerging in the potential of new devices based on active interfaces between ferroelectric oxides and polar semiconductors such as GaN or ZnO. YMnO@sub 3@ is an obvious candidate of oxide films on GaN because they both have a hexagonal lattice structure and the lattice constant of YMnO@sub 3@ is approximately twice that of GaN. Here we report on the epitaxial growth of YMO thin films directly on GaN using MBE. YMnO@sub 3@ films are grown on GaN (0001)-on-sapphire templates using MBE. The structure of the films as characterized by in-situ RHEED, x-ray diffraction, and atomic force microscopy will be discussed. Atomic force microscopy revealed that the YMnO@sub 3@ films grown at different temperatures have significantly different morphologies. Samples grown at the optimal growth temperature are ferroelectric at room temperature, and magnetic at low temperatures. The YMnO@sub 3@ samples exhibit a remnant polarization of approximately 3.2 @micro@C/cm@super 2@ and saturation polarization of about 12 @micro@C/cm@super 2@. The difference between magnetic field-cooled and zero-field-cooled behavior at low temperatures suggests the presence of either antiferromagnetic frustration or ferromagnetic behavior. The effects of different growth temperatures and post-growth annealing will also be discussed. This research was supported by US Office of Naval Research (Grant N00014-02-1-0974), the US Air Force Office of Scientific Research (MURI Grant F49620-03-1-0330), and by the US National Science Foundation through the West Virginia EPSCoR program.