Electrical properties of fully strained boron-doped Si0.90-yGe0.10Cy/n-–Si grown by low pressure chemical vapor deposition have been investigated as a function of carbon content (0.2%–1.5%), using the variable temperature (25–650 K) Hall-effect technique. The results of Hall-effect measurements show that the Si substrate and the SiGeC/Si interfacial layer affect significantly the electrical properties of the SiGeC epitaxial layer. Thus, a three-layer conducting model has been used to extract the carrier concentration and mobility of the SiGeC layer alone. At room temperature, the hole carrier concentration decreases from 6.8×1017 to 2.4×1017 cm-3 and the mobility decreases from 488 to 348 cm2/V s as the carbon concentration increases from 0.2% to 1.5%. The boron activation energy increases from 20 to 50 meV as C increases from 0.2% to 1.5% with an increment of 23 meV per atomic % of C. © 2000 American Institute of Physics.