Stimulated THz Emission of Strained p-Ge and SiGe/Si Quantum-Well Structures Doped with Shallow Acceptors

The origin and properties of stimulated terahertz (THz) emission in uniaxially compressed p-Ge and strained SiGe/Si quantum-well structures doped with shallow acceptors are discussed. The THz emission is associated with the stimulated optical transitions between resonant and localized acceptor states. Spectra of the emission are presented. The regimes of emission excitation and possibility of cw operation are examined.