Numerical Simulation of Semiconductor Devices and Circuits for THz Applications

• Applicant: Professor Dr.-Ing. Christoph Jungemann
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 322069477

The overall goal is to develop a simulation framework for semiconductor devices embedded in circuits for detection and generation of THz signals and to explore new device and circuit concepts.The usual semiconductor equations, on which the commercial TCAD suites are based, will be extended to the case of THz signals by inclusion of the acceleration term, which will enable the simulation of plasma waves in 2D and 3D devices.In addition, we will go beyond the drift-diffusion approximation (e.g. energy transport or hydrodynamic models), because this approximation fails for high mobilities and short channels. The necessary transport and noise parameters will be generated by microscopic simulation methods based on the Boltzmann transportequation, which are available at the ITHE. These tools will be also used to assess the accuracy of the simpler transport models under homogeneous conditions and in the case of devices. The changes in the semiconductor equations will degrade their numerical properties and new stabilization concepts beyondthe Scharfetter-Gummel stabilization scheme have to be developed, where the special restrictions of the semiconductor equations have to be considered (e.g. negative particle densities are physically impossible).Since the fundamental operating principles of THz circuits for detection or generation of THz signals are based on nonlinear effects, a large-signal approach is required. The resultant discrete system of equations for the semiconductor devices will be formulated in a compact form, because the analysis of THz circuits requires a huge amount of simulations for optimizing both the device and the surrounding circuitry. Due to the nonlinearity, each setting requires a full large-signal analysis. In the case of a large signal analysis, we will apply the spline-wavelet-based approach in combination with the multi-rate PDE technique. Techniques for estimating the oscillation frequency are to be developed which canhandle huge system sizes, based on the proposer's former work. In addition, we will implement basic methods for noise calculation.With the newly developed simulation framework, we will investigate key figures of merit of THz detector and generator circuits.For example, we will investigate how standard silicon MOSFETs (bulk or FDSOI) including all parasitics perform in THz detector circuits and how bias conditions and the termination of the device ports influence the responsivity. Furthermore, we will evaluate the suitability of different device concepts for THz generation. We will investigate whether it is possible to generate THz radiation by plasma waves under realistic conditions (e.g. room temperature). Since currently a large number of novel device concepts are suggested, we will flexibly adapt our research to the most promising ones.

• DFG Programme: Research Grants
• International Connection: Austria
• Partner Organisation: Fonds zur Förderung der wissenschaftlichen Forschung (FWF)
• Cooperation Partner: Professor Dr.-Ing. Hans Georg Brachtendorf