Intersubband electroluminescence from silicon-based quantum cascade structures

The quantum cascade laser, which uses electronic transitions within a singl e band of a semiconductor, constitutes a possible way to integrate active o ptical components into silicon-based technology. This concept necessitates a transition with a narrow Linewidth and an upper state with a sufficiently Long Lifetime. We report the observation of intersubband electroluminescen ce from a p-type silicon/silicon-germanium quantum cascade structure, cente red at 130 millielectron volts with a width of 22 millielectron volts, with the expected polarization, and discernible up to 180 kelvin. The nonradiat ive Lifetime is found to depend strongly on the design of the quantum well structure, and is shown to reach values comparable to that of an equivalent GaInAs/AlInAs Laser structure.