Gaseous HCl was used, instead of Secco or Schimmel etching solutions, to reveal the threading dislocations in thick SiGe virtual substrates (VS). The latters, which consisted in linearly graded layers (similar to 8-9% Ge/mu m) capped with more than 1 mu m thick constant composition SiGe layers, were grown at high temperatures on Si(001). Advantages of this revelation techniquewere obvious: HCl selective etching of the defectswas indeed performed on full wafers in the very same chamber used for epitaxy, not on cleaved pieces of wafers in dedicated wet benches which contain toxic chromium ions. Reproducibility was thus better. The etch temperature was reduced from 772 C down to 700 degrees C as the Ge content increased from 20% up to 50%, in order to have the same HCl etch rates (similar to 14nmmin.(-1)). An automated light inspection tool was used to acquire polar maps of the inverted pyramid etch pits after the removal of similar to 120nm, 230 and 340nm of SiGe. The etch pit size increased linearly with the HCl etched thickness and somewhat linearly with the Ge content (20%, 30%, 40% or 50%). The Etch Pits Density (EPD) increased from the center towards the edges of the SiGe VS (similar to 1.6 x 10(5) cm(-2) up to 6 cm away from it. 2.7 x 10(5) cm(-2) 2.7 x 10(5) cm(-2) 9 cm away from it). Very similar mean EPDs, in the 1.75-2.05 x 10(5) cm(-2) range, were otherwise obtained irrespectively of the Ge content and the etched thickness. The EPD in SiGe VS depends instead on the growth temperature, the growth rate and the grading used. (c) 2013 Elsevier B.V. All rights reserved.