Photoluminescence and electrolul11inescence of selforganised grown SiGe dots buried in Si

A study of photoluminescence and electro luminescence of SiGe dots buried in Si is reported, and comparison made with structures containing smooth SiGe layers. The SiGe dot structures were fabricated by low pressure chemical vapour deposition using the Stranski–Krastanov growth mode (island growth). It is shown that the localisation of excitons in the dots leads to an increase of the luminescence efficiency at low excitation compared with smooth SiGe layers (e.g. quantum wells). This is explained by the reduction of competitive non-radiative recombinations at impurities or defects. At higher excitation the efficiency decreases, which is attributed to non-radiative Auger recombination processes in the dots.MST/3290