Phonon-pumped SiGe-Si interminiband terahertz laser

The first phonon-pumped semiconductor laser has been proposed and theoretically investigated. The active region is an unbiased boron-doped Si/sub 0.94/Ge/sub 0.06/-Si superlattice with Si/sub 0.97/Ge/sub 0.03/ buffer layers embedded in a surface-plasmon strip waveguide. Warm and cool heat sinks create a temperature gradient across the waveguide. A heat buffer layer adjacent to the cool sink reflects optical phonons and transmits acoustic phonons, Within the resonator, the difference in effective temperatures of optical and acoustic phonons provides hole pumping for the lasing transition between the heavy-hole 2 (HH2) and heavy-hole 1 (HH1) minibands. A gain of 280/cm at the 5 THz emission frequency is predicted for 6/spl times/10/sup 17//cm/sup 3/ doping at temperatures of 300 K and 77 K for optical and acoustic phonons, respectively. A range of operating conditions in phonon-pumped IV-IV, III-V, and II-VI materials appears feasible.