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Single Photon Laser Ionization as an In-Situ Diagnostic for MBE Growth
Published online by Cambridge University Press: 22 February 2011
Abstract
Single photon laser ionization time-of-flight mass spectroscopy (SPI-TOFMS) is used to monitor the gaseous fluxes of Ga and Asn, during molecular beam epitaxy of GaAs. This noninvasive and real-time probe measures densities, and hence fluxes, of multiple chemical species impinging on or scattered from a substrate during conventional MBE. With single photon ionization at 118 nm (10.5 eV, ninth harmonic of Nd:YAG laser), the photon energy is large enough to ionize the species, but insufficient to both ionize and fragment. The lack of molecular dissociation of As2 and As4 greatly simplifies the interpretation of mass spectra. Additionally, the geometry of the single photon ionization TOFMS permits simultaneous film growth monitoring using RHEED. Results will be presented on the probing of scattering and desorption of III-V MBE species during GaAs growth. This technique promises to be a valuable in-situ diagnostic for III-V and II-VI MBE.
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- Copyright © Materials Research Society 1994
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