A review will be presented of recent work on Si/SiGe heavy-hole to heavy-hole quantum cascade emitters showing progress towards a laser using the bound-to-continuum design for the active region. The sample was grown by low energy plasma enhanced chemical vapour deposition in significantly less time than comparable structures and designs in III-V or Si/SiGe technology using molecular beam epitaxy or more standard chemical vapour deposition techniques. Clear intersubband electroluminescence is demonstrated at 4.2 K between 6.7 and 10.1 THz. This is inside the III-V restrahlung band where III-V materials cannot lase, unlike Group IV materials. A review of waveguide losses will also be presented and some ideas of how to design an active region with gain higher than the waveguide losses will be discussed.