The photoconductance decay lifetime in pseudomorpically strained <100> Si/Si0.7Ge0.3 heterostructures grown by rapid thermal chemical vapor deposition is measured in heterostructures with and without oxygen and carbon at the interface between the silicon substrate and epitaxial Si0.7Ge0.3 layer. A standard ex-situ clean combined with an in-situ hydrogen cleaning step using different combinations of hydrogen flows (0-20 slpm), pressure (80-8.8 x 10(4) Pa), and temperature (760-865 degreesC) are used to produce high oxygen and or carbon concentrations at the interface, measured by secondary ion mass spectrometry. For all cases in which oxygen was detected at the interface the heterostructure's lifetime were significantly shorter, 55-113 mus, compared to that in device quality Si/Si0.7Ge0.3 heterostructures, 530 mus, grown using a 1 min, 900 degreesC in-situ hydrogen bake that regularly reduces oxygen and carbon contamination below SIMS detection limits. Numeric simulations of the Si/Si0.7Ge0.3 heterostructures indicate that increasing recombination at the interface leads to a saturation of the lifetime at approximately 55 mus due to electron transport limited recombination at the Si/SiGe interface, consistent with the experimental observations. (C) 2004 Elsevier B.V. All rights reserved.