Cathodoluminescence and EBIC study on misfit dislocations in SiGe/Si heterostructure

Optical and electrical activities of misfit dislocations in SiGe/Si films were studied by means of Cathodoluminescence (CL) and electron beam induced current (EBIC) technique. The dominant type of dislocations were densely spaced dislocations and isolated dislocations running along the two 〈110〉 directions identified by X-ray topographs. Strong D2, D3 and D4 luminescence was observed from the densely spaced dislocations, while weak D1 luminescence was observed at some regions where dislocations intersect each other. The intensity distribution of D2 luminescence is nonuniform along misfit dislocations compared with that of D3. No D-line luminescence was observed from isolated dislocations. Both densely spaced dislocations and isolated dislocations are EBIC active below 200 K, indicating that they are free from serious metallic contamination. The ratio of radiative recombination to total recombination at a region of densely spaced dislocations is less than 1%, which suggests that the energy state of dislocation spreads in the momentum space.