The electrical activities of dislocations in a SiGe/Si heterostructure were examined by deep-level transient spectroscopy after iron contamination and phosphorous diffusion gettering. Deep-level transient spectroscopy of iron contaminated samples revealed a peak at 210K, which was assigned to individual iron atoms or very small (<2nm) precipitates decorated along dislocations, considering that the iron contamination annealing was terminated by quenching and transmission electron microscopy did not reveal any precipitate at dislocations. Arrhenius plot of the 210K peak yielded a hole capture cross section of 2.4 x 10−14cm2 and an energy level of 0.42eV above the valance band. The relatively large hole capture cross section indicated strong interactions between iron-related deep levels and the dislocation shallow bands. Deep-level transient spectroscopy of the iron contaminated sample revealed that 6 x 1014/cm3 of boron could more effectively trap interstitial iron at room temperatures than the strain field/defect sites at 107 to 108 dislocations/cm2. Phosphorous diffusion experiments revealed that the gettering efficiency of iron impurities depends on the dislocation density. For regions of high dislocation density, phosphorous diffusion could not remove all iron impurities decorated at dislocations, suggesting a strong binding of iron impurities at dislocation core defects.

Investigation of Iron Impurity Gettering at Dislocations in a SiGe/Si Heterostructure. J.Lu, X.Yu, Y.Park, G.Rozgonyi: Journal of Applied Physics, 2009, 105[7], 073712