Deterministic simulation of electron and phonon transport in III-V devices

• Applicant: Professor Dr.-Ing. Christoph Jungemann
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; Microsystems
• Term: from 2013 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 215913023

• Final Report Year: 2023

Final Report Abstract

The electron mobility and saturation velocity in III–V materials are much higher than in silicon, and III–V heterojunction bipolar transistors (HBT) are therefore much faster than their silicon siblings. On the other hand, quasi-ballistic transport in III–V HBTs degrades the accuracy of the standard TCAD (Technology Computer-Aided Design) tools (e.g. drift-diffusion (DD) model), which hinders the computer-aided design of new III–V devices. The development of more accurate TCAD-Tools requires the use of a more fundamental approach than the DD model. In the semi-classical framework this is the Boltzmann equation (BE), from which the TCAD models can be derived under certain approximations. In this project we developed a deterministic solver for the BE, which is stable regardless of the strength and type of scattering. The BE is directly discretized in the k-space and Godunov’s scheme is applied to the free streaming operator after moving the forces into the interfaces between the cells of the real space grid. We implemented algorithms for the stationary, small-signal and transient cases as they occur in typical TCAD problems. In order to simulate a state-of-the-art InP/InGaAs double heterojunction bipolar transistor (DHBT), we modeled the various III–V materials based on model parameters taken from literature and by matching experimental data available in the literature. With the resultant models we generated with the BE transport parameters for the TCAD models (e.g. electron majority and minority mobilities as a function of the doping concentration, electric field, material composition etc.). The TCAD models contain device specific parameters that we determined by BE device simulations. Still unknown parameters (e.g. band alignment at heterojunctions) were matched to the measurements and in an iterative process a complete device model was derived that showed good agreement with the experimental device characteristics. Finally, the device results of the BE were used to assess the accuracy of a newly developed augmented DD model.

Publications

• A Godunov-Type Stabilization Scheme for Large-Signal Simulations of a THz Nanowire Transistor Based on the Boltzmann Equation. IEEE Transactions on Electron Devices, 68(11), 5407-5413.
  Noei, Maziar; Linn, Tobias; Luckner, Paul & Jungemann, Christoph
  
• “A Godunov-type stabilization scheme for solving the stationary and transient Boltzmann transport equation,” Proc. IWCE International Workshop on Computational Nanotechnology, pp. 95-96, 2021
  Luckner, P.; Leenders, H.; Linn, T.; Noei, M. & Jungemann, C.
  
• Physical Modeling of InP/InGaAs DHBTs With Augmented Drift-Diffusion and Boltzmann Transport Equation Solvers—Part I: Simulation Tools and Application to Sample Structures. IEEE Transactions on Electron Devices, 70(10), 5065-5072.
  Leenders, Hendrik; Müller, Markus; Jungemann, Christoph & Schröter, Michael
  
• Physical Modeling of InP/InGaAs DHBTs With Augmented Drift-Diffusion and Boltzmann Transport Equation Solvers—Part II: Application and Results. IEEE Transactions on Electron Devices, 70(10), 5073-5080.
  Müller, Markus; Leenders, Hendrik; Jungemann, Christoph & Schröter, Michael