Electroluminescence from Si/SiGe quantum cascade emitters

Intersubband electroluminescence results are presented from Si/SiGe quantum cascade emitters at 3.2 THz and at temperatures up to 150 K. The effect of adding doping into the active quantum wells was studied in addition to reduced barrier widths from previous measurements. While the current through the sample is increased by the addition of doping, the emitted power is reduced through additional free carrier absorption and Coulombic scattering. Free electron laser measurements confirm the intersubband transitions in the quantum wells of the cascade devices and produce non-radiative lifetimes of 20 ps between 4 and 150 K.