The research contents mainly include the studies of: physical mechanism of the semiconductor terahertz oscillator, the formation and propagation of the spatio-temporal electric field domain, fundamental characteristics of the current oscillation in quantum wells, super-lattices, and quantum dots, THz radiation in the semiconductor intersubbands and solid state semiconductor THz device, the development of transport theory, the magneto-photon-phonon-plasma resonance in semiconductor and optical medium, solid THz detector and oscillator.