Semiconductor structures (52-9, 52-11, 52-12) and methods (100-300) are provided for a semiconductor devices employing strained (70) and relaxed (66) semiconductors, The method comprises, forming (106, 208, 308) on a substrate (54, 56, 58) first (66-1) and second (66-2) regions of a first semiconductor material (66) of a first conductivity type and a first lattice constant spaced apart by a gap or trench (69), filling (108, 210, 308) the trench or gap (69) with a second semiconductor material (70) of a second, conductivity type and a second different lattice constant so that the second semiconductor material (70) is strained with respect to the first semiconductor material (66) and forming (110, 212, 312) device regions (80, 88, S, G, D) communicating with the first (66) and second (70) semiconductor materials and adapted to provide device current (87, 87') through at least part of the strained second semiconductor material (70) in the trench (69). In a preferred embodiment, the relaxed semiconductor material is 80:20 Si:Ge and the strained semiconductor material is substantially Si.