Electroluminescence from Strained Si/SiGe/Si Heterostructure Diodes

In this work we present a detailed study of the electroluminescence properties of Si1-xGex/Si double heterostructure diodes. The diodes were grown selectively by low pressure chemical vapor deposition which enables to grow dislocation-free and fully strained Si1-xGex layers much above the critical thickness. The electroluminescence is shown to be due to the recombination of free excitons at lower temperatures. The decrease of luminescence intensity with increasing temperature above 80K seems to be determined mainly by the thermal emission of the holes from the Si1-xGex layer. The estimated quantum efficiency of 10^¿3 - 10^¿4 and the relatively short lifetime of about 90ns show that competing nonradiative recombinations are still dominant. These nonradiative recombinations seem to take place at recombination centers.