Low-power pulsed-laser annealing ͑LPPLA͒ was applied to III-V compound semiconductors GaAs and InP. The effects have been analyzed using several experimental techniques such as reflection high-energy electron diffraction, Rutherford backscattering spectroscopy, x-ray photoelectron spectroscopy, and electrical measurements. In addition, a calculation method was developed to study the heat propagation in the irradiated sample during the LPPLA process. The irradiation conditions, realizing a uniform surface laser-energy distribution, made possible a unidimensional approach. The results obtained experimentally and by numerical modeling agree well if one assumes that a solid-phase epitaxy takes place. The XPS measurements for GaAs and InP show, in particular, that a range of the irradiation power density exists where the LPPLA can effectively restore the lattice order without appreciable alteration of the surface stoichiometry. At higher power density of irradiation, the As and P vacancies introduced by the laser, in GaAs and InP, respectively, may no longer be neglected.
High resolution transmission electron microscopy has been used to investigate the lattice damage distribution in Zn+ implanted and implanted plus low-power pulsed-laser annealed (LPPLA) GaAs. The damage distribution of implanted samples has been examined in detail showing the presence of a continuous amorphous layer under the surface and stacking fault tetrahedra nuclei at the inner a–c interface. A solid phase epitaxial regrowth of ion implanted GaAs has been induced by LPPLA technique. In the annealed samples, the crystalline recovering is characterized by a low density of residual extended defects lying in the fully recrystallized amorphous layer.
The effects of the ambient atmosphere in the annealing chamber on the electrical and structural characteristics of Zn-implanted III-V compound semiconductors, processed by low-power pulsed-laser annealing are presented. The samples were analyzed using several complementary experimental techniques: Reflection highenergy electron diffraction, Rutherford backscattering spectroscopy, Raman spectroscopy, secondary ion mass spectroscopy, and electrical measurements. During the laser beam irradiation in the presence of gas inlet into the annealing chamber the ambient gas atoms diffused well into the target changing the stoichiometry and the electrical parameters. Redistribution of the implanted impurity was also observed. By varying the type of gas used and its pressure, it was possible to achieve electrical activation of up to 80%. It seems all structure and electrical parameters achieve their best values at the same ambient atmosphere and density of the deposited laser power P, e.g., 1.5 atm of N 2 and Pϭ6.5 MW/cm 2 for InP.
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