Epitaxial growth of III-V semiconductor materials is probed in a molecular beam epitaxy reactor by single photon ionization of the gaseous fluxes using vacuum ultraviolet (VUV) laser radiation. The ninth harmonic of the Nd:YAG laser is produced by frequency tripling the output to 355 nm and then to 118 nm in a Xe/Ar mixture. Together with a time-of-flight mass spectrometer, this radiation is used to selectively probe the gaseous fluxes of Ga, As, As₂, and As₄ during molecular beam epitaxy of III-V materials. The essential aspects of the method and details of calibration procedures to obtain relative fluxes are described. Cracking of the arsenic species does not occur in the laser/mass spectrometer, making relative species concentration measurements very reliable. Rapid data acquisition provides real time measurements of the fluxes of incident and scattered or desorbed materials during growth. Several basic examples are considered, including the thermal cracking of As₄ on silicon and the desorption of arsenic and gallium species from GaAs during epitaxial growth. Recent work to correlate the flux determinations with reflection high energy electron diffraction (RHEED) oscillations during GaAs epitaxial growth is discussed.

Date Published: 14 September 1994
PDF: 10 pages
Proc. SPIE 2282, Ultraviolet Technology V, (14 September 1994); doi: 10.1117/12.186629

Published in SPIE Proceedings Vol. 2282:
Ultraviolet Technology V
Robert E. Huffman; Christos G. Stergis, Editor(s)