In this paper, we report on current pumped THz emitting devices based on intersubband transitions in SiGe quantum wells. The spectral lines occurred in a range from 5 to 12 THz depending on the quantum well width, Ge concentration in the well, and device temperature. A time-averaged power of 15 nW was extracted from a 16 period SiGe/Si superlattice with quantum wells 22 ? thick, at a device temperature of 30 K and a drive current of 550 mA. A net quantum efficiency of approximately 3 × 10-4 was calculated from the power and drive current, 30 times higher than reported for comparable quantum cascades utilizing heavy-hole to heavy-hole transitions and, taking into account the number of quantum well periods, approximately four times larger than for electroluminescence reported previously from a device utilizing light-hole to heavy-hole transitions.
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