Plasma Wave Detector Of Terahertz Radiation

Terahertz(THz) detector is an active research field in recent years. Plasma wave excitation in submicron field effect transistors and related device structures should allow us to develop a new generation of solid-state terahertz tunable terahertz devices that will find numerous applications in industry, defense, and biotechnology. In this thesis, a detailed discussion of plasma wave instability in the high-electron-mobility transistor (HEMT) driven by the terahertz radiation is presented. The results can be easily applied to the design and use of terahertz detector. The main contents and conclusions are as follows:1. By calculating the continuous function and Euler function, we investigate the plasma oscillation in field effect transistors and the instabilities of these waves in different device structures. It's found that the plasma oscillation results in a periodic variation of the channel charge. This can be used for detection of the terahertz radiation.2. We theoretically study the high-electron-mobility transistor driven by the terahertz radiation, and calculate the gate-to-source/drain admittance and the detection responsivity of the HEMT as a function of the signal frequency. It is found that the peaks of the admittances and the responsivities show redshift, and the heights of the peaks decrease with increasing the lengths of the source-to-gate and gate-to-drain spacings. Such phenomena can be useful in design of different HEMTs utilizing the effects associated with the plasma oscillations excitation.3. We theoretically investigate the plasma-wave instability mechanism in a two-dimensional electron fluid in a high-electron-mobility transistor driven by the terahertz radiation in the presence of a perpendicular magnetic field. It is found that the resonant peaks of the gate-to-source/drain admittances and detection responsivity depend on the intensity of the external magnetic field. Such phenomena can be useful to adjust the intensity of the magnetic field in order to bring about the desired effect.