Hyperfine interactions of111In→111Cd probe atoms on GaAs (111)B reconstructed surfaces
We have used111In→111Cd perturbed-angular-correlation (PAC) spectroscopy to measure hyperfine interactions at surface sites on two molecular-beam-epitaxy-grown GaAs (111)B (As-terminated) reconstructed surfaces. The PAC measurements performed on the 2×2 reconstructed surfaces show two well-defined nuclear electric-quadrupole interactions that occur at two inequivalent Ga-sites on the surface. The measurements performed on the √19×√19 R 23.4° reconstructed surfaces show primarily one well-defined interaction to which corresponds a large and asymmetric EFG, in which the EFGz-axis is oriented essentially perpendicular to the surface. Annealing experiments were performed to convert one reconstruction to the other and then to reconvert it back to the original reconstruction, e.g., 2×2→√19×√19 R 23.4°→ 2×2. The PAC measurements that followed each annealing step show the characteristic frequencies for each reconstruction. This result indicates that these probe sites are thermodynamically stable. In this report, we present a brief description of the experiment and, as an example, one series of measurements that illustrates the results of an extensive investigation, which reports the first measurements of group-III bonding symmetries on a compound III–V semiconductor surface.
KeywordsGaAs Hyperfine Interaction Surface Site Extensive Investigation Reconstructed Surface
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