The mobility behavior of boron delta (delta)-doped Si, Si1-xGex(0 less-than-or-equal-to x less-than-or-equal-to 1) is investigated, which includes the first mobility measurements reported for B delta-doped Si1-xGex and Ge. The expected mobility enhancement from delta doping is not realized in Si:B due to the heavy effective mass of holes. However, some enhancement may be possible at lower doping levels for narrower wells. Indications of mobility enhancement have been realized for delta-doped Ge:B because of the relatively light effective mass. We also present the implementation of boron delta-doped layers in the fabrication of (i) the first SiGe:B delta-FET and (ii) the first coupled delta-layer Si:B delta-FET.