Semiconductors and nanostructures-based sources of terahertz radiation

A review of several approaches to obtaining the emission of terahertz spectral range based on the use of semiconductor micro- and nanostructures is presented. Physical principles of terahertz sources based on impurity related carrier transitions including transitions involving resonant impurity states and on carrier heating in strong electric field are discussed. Emitter of millimeter radiation based on transit time resonance in n-InP is described and the way to rise the frequency up to several THz is suggested