Characterization of High Purity Si-Doped Molecular Beam Epitaxial GaAs.
Technical rept. 1 Nov 83-1 Nov 84,
ILLINOIS UNIV AT URBANA ELECTRICAL ENGINEERING RESEARCH LAB
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High purity, lightly Si-doped MBE GaAs layers have been characterized using variable-temperature Hall effect and C-V measurements, photothermal ionization spectroscopy, low-temperature photoluminescene PL, and deep level transient spectroscopy DLTS. The spectroscopic measurements of the residual donors and acceptors indicate that the pronounced increase in carrier concentration which is observed with increasing As flux for a constant Ga flux results from incorporation of additional residual S donors from the As source material, and not from reductions in the Si acceptor concentration or residual C acceptor concentration. The increase in carrier concentrations with As flux is considerably more pronounced when using an alternative source of As, which introduces both S and 3 additional donor species. The C acceptor concentration increases with As flux using either As source, although the increase is much stronger with the alternative source. The dependence of C concentration on the As source implies that the As source itself contributes at least part of the C background. The Si acceptor concentration is negligible for the range of growth conditions that were used.