Axial dechanneling

Defects in ion implanted and laser irradiated GaAs

“…the nature of these defects was found by a careful defect analysis of the backscattering minimum yield for different temperatures as described in Ref. 3. Preliminary experiments show that large concentrations ( -50%) of point defects with small distances from the lattice site are most probable, which is consistent with the conclusion from the optical data.…”

“…This is also true if we take into account the generation of defects during the measurements because they yield an increase of x,,,, which is smaller than the difference of AX,,,, for 60 K and 293 K. The existence of such a negative temperature dependence of AX,,,,, was predicted in Ref. 3 for displaced atoms (point defects) positioned near the strings, but has never been measured up to now. In the following the possibility of a quantitative analysis of the preliminary experimental data is discussed.…”

“…3 the main information about the position of the point defects is given by the temperature dependence of Ax,,,,. For the defect distributions given in Figure 3b with the corresponding q, values the differences in the minimum yield A X~, J Z ) at 60 K were calculated.…”

“…Using the method described in Ref. 3 and also applied in Ref. 13, the relative concentration of point defects n,&) as a function of the depth z as well as its position (distance r,, from the strings of atoms) can be determined if the minimum yield is measured for different temperatures.…”

“…Using the procedure described in Ref. 3 we have calculated the concentration n,,(z) from the smoothed experimental curve Ax,,,,(z) for the measurement temperature 293 K (Figure 3a), assuming different fixed values of the distance r , from the string and for randomly distributed r, (no preferred position).…”