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Proceedings Paper

In Situ Optical Measurements Of The Growth Of GaAs and AlGaAs By Molecular Beam Epitaxy
Author(s): D. E. Aspnes; J. P. Harbison; A. A. Studna; L. T. Florez; M. K. Kelly
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Paper Abstract

We discuss the first real-time spectroscopic measurements of (001) GaAs and AlAs surfaces during crystal growth by MBE. Reflectance-difference spectroscopy (RDS) is used to enhance the typically low sensitivity of optical probes to these surface phenomena. We describe a photoelastic-modulator optical-bridge configuration that achieves a sensitivity of 5 x 10-5 to reflectance-difference (RD) signals under actual growth conditions, and use it to obtain the dynamic surface response for changes under various growth conditions. Comparison of RD and reflection high energy electron diffraction (RHEED) signals upon interruption of the As flux during otherwise normal growth of GaAs and AlAs show that RD signals are sensitive to either surface chemistry or surface structure according to photon energy. The spectral dependence of the chemically sensitive component is sufficiently pronounced so that Al- and Gaterminated surfaces can be distinguished. We use this capability to assess the competition between codeposited Al and Ga for the same surface-bonding sites. We also discuss the first observation of the RD analog of RHEED oscillations upon initiation of crystal growth, for both chemically and structurally sensitive conditions. Our results suggest that systematic investigations of the optical properties of growth surfaces will lead to a new understanding of crystal growth and new opportunities for the control of crystal growth processes.

Paper Details

Date Published: 9 August 1988
PDF: 10 pages
Proc. SPIE 0946, Spectroscopic Characterization Techniques for Semiconductor Technology III, (9 August 1988); doi: 10.1117/12.947419
Show Author Affiliations
D. E. Aspnes, Bellcore (United States)
J. P. Harbison, Bellcore (United States)
A. A. Studna, Bellcore (United States)
L. T. Florez, Bellcore (United States)
M. K. Kelly, Bellcore (United States)

Published in SPIE Proceedings Vol. 0946:
Spectroscopic Characterization Techniques for Semiconductor Technology III
Orest J. Glembocki; Fred H. Pollak; Fernando A. Ponce, Editor(s)

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