X-RAY SCATTERING FROM MICRODEFECTS. E. Gartstein and D. Mogilyanski Inst. for Appl. Research, Ben-Gurion University, POB 653, Beer-Sheva, 84105, Israel

Knowledge of structure perfection in single crystal materials used for fabrication of devices, allows better control of their electronic properties. Microdefects resulting from clustering of point defects or dislocation loops, are common in these materials. X-ray scattering is very sensitive to the presence of these defects, particularly in transmission mode, when the concentration is low. Analysis can be performed to obtain information on the nature, size and concentration of the defects. Triple-crystal diffractometry was employed to measure anomalously transmitted X-ray scattering in InP. Metallographic studies of InP crystals showed the presence of the dislocation loops with the uncertainty regarding their system type:{111} < 110 > or {110} <110>. Simulation of the Huang scattering and comparison with the symmetric intensity component 1/2[I(q) + I(-q)] obtained from the measurements, indicated that - dislocation loop system is consistent with {111} < 110 > interstitial model. However, the measured antisymmetric intensity component 1/2[I (q) - I(-q)] where q is the momentum transfer near to the peak (022), was about 90deg. rotated as shown in Fig. la, while the theory predicts the positive (solid lines) and negative (dashed lines) intensity contours to be located along the reciprocal lattice vector as is shown in Fig. lb. This feature could be explained by including into simulation of the diffuse scattering its asymptotic part and considering the possibility of the vacancy loops to be present as well. The rotation of the antysymmetric intensity resulted when vacancy loops occupy the (111) plane and the rest of the {111} planes are occupied by interstitial loops as is shown in Fig. 1c

Fig.1