Electrostatic THz Excitation in Semiconductor Plasmas

Abstract

The THz spectrum excited by an external electron beam is studied in semiconductor systems. The beam electrons interact with the medium particles to excite a wave at the cyclotron frequency. The dispersion relation of the THz spectrum is obtained by employing the quantum magneto-hydrodynamic (QMHD) model for the semiconductor species, which includes quantum features like Landau quantization of Fermi statistical pressure. It is noticed that the dispersion relation verifies the excitation of THz electron cyclotron waves (ECWs) at a typical set of real-time parameters of GaAs semiconductor plasmas. The features of the THz spectrum vary with varying angles of propagation \(\theta \) that exist between the wave vector k of the spectrum and the ambient magnetic field \(B_0\), the streaming speed of the electron beam \(u_{0}\) directed into the plasma system parallel to wave vector k, the thermal effects of beam electrons, and the gyro frequency dependent on \(B_0\) rooted in the expression of Landau quantization. As for the application, this study is helpful to understand semiconductor device technology. The semiconductors are used to generate the THz range by continuous waves or pulse waves [1] although they face a lot of technical difficulties in the laboratory [2]. A theoretical model is presented here for the excitation of continuous plasma waves [3], employing the data of GaAS semiconductors for the THz range [4]. The authors believe that this study may increase our theoretical understanding to meet the growing demand for THz bandwidth for experimental purposes.