The arsenic (As) diffusion behavior through a strained Si/relaxed Si1-xGex heterostructure having Ge contents x of 0.15, 0.20, and 0.25 has been investigated using a thermal-diffusion method in order to avoid the crystal damage associated with ion implantation. As-concentration profiles through a strained Si/Si1-xGex heterostructure obtained by secondary-ion mass spectroscopy are in approximate agreement with a simple erfc distribution. The diffusion coefficient of As increases with an increase in the Ge content. The diffusion coefficient of Ge in strained Si is almost the same within errors, irrespective of Ge content. (C) 2008 The Electrochemical Society.