Photoluminescence spectra of deformed Si-Ge alloy

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Abstract
We measured photoluminescence (PL) spectra of deformed bulk Si-Ge alloys and found peculiar peak shifts of D1 and D2 lines depending on the deformation and annealing temperatures. Alloy crystals were grown by the Czochralski method. Specimens were deformed by compression at temperatures between 700 and 900 °C in an argon atmosphere. PL spectra were measured at 4.2 K. Peak positions of D1 and D2 lines depended on the deformation temperatures; they were at higher energies at higher deformation temperatures. On the other hand, those of D3 and D4 did not depend on the deformation temperature. The magnitudes of peak shifts of D1 and D2 lines were proportional to t2/3 at small t due to isothermal annealing ( t: the duration of annealing) at around 650 °C. The activation energy was determined to be 2.5 eV, which was much smaller than that of self-diffusion. These results were interpreted as being due to the change of alloy composition around dislocations caused by the elastic interaction between dislocations and constituent atoms, i.e., Si and Ge, in which process point defects generated during deformation were thought to play a crucial role.