PHOTOLUMINESCENCE AND ELECTROLUMINESCENCE OF SELFORGANISED GROWN SIGEDOTS BURIED IN SI

A study of photoluminescence and electroluminescence of SiGe dots buri ed in Si is reported, and comparison made with structures containing s mooth SiGe layers. The SiGe dot structures were fabricated by low pres sure chemical vapour deposition using the Stranski-Krastanov growth mo de (island growth). It is shown that the localisation of excitons in t he dots leads to an increase of the luminescence efficiency at low exc itation compared with smooth SiGe layers (e.g. quantum wells). This is explained by the I eduction of competitive non-radiative recombinatio ns at impurities or defects. At higher excitation the efficiency decre ases, which is attributed to non-radiative Auger recombination process es in the dots.