The Microscopic Mechanisms of Nonlinear Rectification on Si-MOSFETs Terahertz Detector

Studying the nonlinear photoresponse of different materials, including III-V semiconductors, two-dimensional materials and many others, is attracting burgeoning interest in the terahertz (THz) field. Especially, developing field-effect transistor (FET)-based THz detectors with preferred nonlinear plasma-wave mechanisms in terms of high sensitivity, compactness and low cost is a high priority for advancing performance imaging or communication systems in daily life. However, as THz detectors continue to shrink in size, the impact of the hot-electron effect on device performance is impossible to ignore, and the physical process of THz conversion remains elusive. To reveal the underlying microscopic mechanisms, we have implemented drift-diffusion/hydrodynamic models via a self-consistent finite-element solution to understand the dynamics of carriers at the channel and the device structure dependence. By considering the hot-electron effect and doping dependence in our model, the competitive behavior between the nonlinear rectification and hot electron-induced photothermoelectric effect is clearly presented, and it is found that the optimized source doping concentrations can be utilized to reduce the hot-electron effect on the devices. Our results not only provide guidance for further device optimization but can also be extended to other novel electronic systems for studying THz nonlinear rectification.

Automated summary

Studying the nonlinear photoresponse of different materials in the terahertz field, especially in developing THz detectors with preferred nonlinear plasma-wave mechanisms, is of great importance for advancing performance imaging or communication systems. Shrinking THz detectors raise concerns about the hot-electron effect on device performance and the elusive physical process of THz conversion. A drift-diffusion/hydrodynamic model was implemented to understand the dynamics of carriers and reveal the competitive behavior between nonlinear rectification and hot electron-induced photothermoelectric effect. The optimized source doping concentrations were found to reduce the hot-electron effect on the devices.