True. All MOS transistors used in the modern CMOS processes used for instance to make CPUs are doped with germanium in their gate regions, in order to produce a strain in the silicon lattice.
While a little strain can be beneficial in some cases, the large strain caused by the mismatches in crystal lattice cell size between various semiconductor layers that must be deposited one over the other in order to make some semiconductor device can cause great problems during manufacturing, by generating various defects that may make the process yield unacceptable.
Because of this, when researching new semiconductor materials a lot of effort is dedicated for finding compositions that can have matched lattice cell sizes.
While a little strain can be beneficial in some cases, the large strain caused by the mismatches in crystal lattice cell size between various semiconductor layers that must be deposited one over the other in order to make some semiconductor device can cause great problems during manufacturing, by generating various defects that may make the process yield unacceptable.
Because of this, when researching new semiconductor materials a lot of effort is dedicated for finding compositions that can have matched lattice cell sizes.