AVS 53rd International Symposium
    Electronic Materials and Processing Wednesday Sessions
       Session EM-WeM

Paper EM-WeM12
In-Situ Investigation of Surface Stoichiometry During YMnO@sub 3@, InGaN and GaN Growth by Plasma-Assisted Molecular Beam Epitaxy Using RHEED-TRAXS

Wednesday, November 15, 2006, 11:40 am, Room 2003

Session: New Directions in Compound Semiconductors
Presenter: R.P. Tompkins, West Virginia University
Authors: R.P. Tompkins, West Virginia University
E.D. Schires, West Virginia University
K. Lee, West Virginia University
Y. Chye, West Virginia University
D. Lederman, West Virginia University
T.H. Myers, West Virginia University
Correspondent: Click to Email
Reflection high-energy electron diffraction total-reflection-angle x-ray spectroscopy (RHEED-TRAXS) can use high-energy electrons from the RHEED electron gun in an MBE growth system to excite x-ray fluorescence. Since the RHEED electrons just penetrate the surface, and by using a geometry that measures x-rays at the total reflection angle, RHEED-TRAXS probes the top 20 to 30 Å of material. Surface coverage of Ga and In during growth of GaN and InGaN was probed using this technique. Studies of the evolution of the surface layer of Ga on GaN during growth at substrate temperatures between 700°C and 750°C will be reported. RHEED-TRAXS measurements were performed during growth of InGaN by measuring the ratio of the In L@alpha@ to Ga K@alpha@ intensity. A significant surface coverage of In was observed at all temperatures investigated regardless of actual In incorporation. RHEED-TRAXS was also used to investigate surface segregation of Mg in GaN, indicating near monolayer coverage. This is useful for studies of the suppression of surface segregation of Mg for p-type doping of GaN, as well as determining a critical Mg surface coverage for polarity inversion. A second RHEED-TRAXS assembly was constructed for use in an oxide MBE chamber at WVU. Preliminary oxide work was performed using the initial RHEED-TRAXS setup, including measurement of monolayer thick layers and determination of the critical angle of Y L@alpha@ and Mn K@alpha@ x-rays. RHEED-TRAXS measurements performed during growth of YMnO@sub 3@ will be discussed. Because RHEED-TRAXS has near monolayer sensitivity, it is a useful tool for determination of conditions for stoichiometric layer-by-layer growth of YMnO@sub 3@. @FootnoteText@ This work was supported by AFOSR MURI Grant F49620-03-1-0330. R.P. Tompkins was supported in part by a grant from the West Virginia Graduate Student Fellowships in Science, Technology, Engineering and Math (STEM) program.