Effect of annealing under stress on defect structure of Si–Ge

Czochralski grown 1 1 1 oriented Si0.986Ge0.014 and Si0.974Ge0.026 samples, with interstitial oxygen concentration 8 × 1017 cm−3, were processed for 5 h at 1270/1400 K (HT), under Ar pressure 105 Pa or 1.1 GPa (HP). Defect structure of Si–Ge was determined by synchrotron topography, high resolution X-ray diffractometry, infrared spectrometry and photoluminescence (PL) measurements. Topography of Si–Ge reveals so-called striations, related to Ge segregation. X-ray diffuse scattering is most pronounced for processed Si0.974Ge0.026; its intensity decreases with HT (HP). Processing, especially under HP, results in a changed lattice parameter, e.g. for Si0.974Ge0.026 processed at 1270 K under 1.1 GPa, a = 0.543444(5) nm while equals to 0.543301(5) nm for the as-grown sample. Intensity of PL at about 1.07 eV, related to the presence of electron hole droplets (EHD), decreased after processing at HT-(HP), evidencing out-annealing of point-like defects. Defects created in Si–Ge are in part related to tiny precipitates of oxygen. Dislocations are practically absent in processed Si–Ge. One can hope to apply HT-HP processing to improve structural perfection of Si–Ge.