Critical modeling issues of SiGe semiconductor devices, Journal of Telecommunications and Information Technology, 2004, nr 1

We present the state-of-the-art in simulation of silicon-germanium (SiGe) semiconductor devices. The work includes a detailed comparison of device simulators and current transport models. Among the critical modeling issues addressed in the paper, special attention is focused on the description of the anisotropic majority/minority electron mobility in strained SiGe grown on Si. We use a direct approach to obtain scattering parameters (S-parameters) and other derived figures of merit of SiGe heterojunction bipolar transistors (HBTs) by means of small-signal AC-analysis. Results from two-dimensional hydrodynamic simulations ofSiGe HBTs are presented in good agreement with measured data. The examples are chosen to demonstrate technologically important issues which can be addressed and solved by device simulation

Multi-dimensional modeling and simulation of semiconductor nanophotonic devices

Self-consistent modeling and multi-dimensional simulation of semiconductor nanophotonic devices is an important tool in the development of future integrated light sources and quantum devices. Simulations can guide important technological decisions by revealing performance bottlenecks in new device concepts, contribute to their understanding and help to theoretically explore their optimization potential. The efficient implementation of multi-dimensional numerical simulations for computer-aided design tasks requires sophisticated numerical methods and modeling techniques. We review recent advances in device-scale modeling of quantum dot based single-photon sources and laser diodes by self-consistently coupling the optical Maxwell equations with semiclassical carrier transport models using semi-classical and fully quantum mechanical descriptions of the optically active region, respectively. For the simulation of realistic devices with complex, multi-dimensional geometries, we have developed a novel hp-adaptive finite element approach for the optical Maxwell equations, using mixed meshes adapted to the multi-scale properties of the photonic structures. For electrically driven devices, we introduced novel discretization and parameter-embedding techniques to solve the drift-diffusion system for strongly degenerate semiconductors at cryogenic temperature. Our methodical advances are demonstrated on various applications, including vertical-cavity surface-emitting lasers, grating couplers and single-photon sources

Industrial Application of Heterostructure Device Simulation,”

Abstract-We give an overview of the state-of-the-art of heterostructure RF-device simulation for industrial application based on III-V compound semiconductors. The work includes a detailed comparison of device simulators and current transport models to be used, and addresses critical modeling issues. Results from two-dimensional hydrodynamic simulations of heterojunction bipolar transistors (HBTs) and high electron mobility transistors (HEMTs) with MINIMOS-NT are presented in good agreement with measured data. The simulation examples are chosen to demonstrate technologically important issues which can be addressed and solved by device simulation

Negative differential mobility in GaAs at ultrahigh fields: Comparison between an experiment and simulations

Direct measurement of the electron velocity v(n) at an extreme electric field E is problematic due to impact ionization. The dependence v(n)(E) obtained by a Monte Carlo method can be verified, however, by comparing simulated and experimental data on superfast switching in a GaAs bipolar transistor structure, in which the switching transient is very sensitive to this dependence at high electric fields (up to 0.6 MV/cm). Such a comparison allows the conclusion to be made that the change from negative to positive differential mobility predicted earlier at E similar to 0.3 MV/cm should not happen until the electric field exceeds 0.6 MV/cm. (c) 2008 American Institute of Physics

Hot-Electron-Related Degradation in InAlN/GaN High-Electron-Mobility Transistors

Hot-electron temperature (T-e) in InAlN/GaN high-electron-mobility transistors (HEMTs) was determined using electroluminescence spectroscopy as a function of gate voltage and correlated with the Te distribution determined by hydrodynamic simulations. Good agreement between measurement and simulations suggests that hot electrons can locally reach temperatures of up to 30 000 K at V-ds = 30 V, i.e., two to three times higher than that typically obtained for similar AlGaN/GaN HEMTs. The consequence of such high Te in InAlN/GaN HEMTs is illustrated by electrical stressing in OFF and semi-ON state at V-gd = 100 V. Prominent channel degradation was observed for devices stressed in semi-ON state, suggesting hot-electron driven degradation. Threshold voltage and drain current transient analyses indicate that hot electrons increase the density of traps in the GaN channel underneath the gate as well as surface/interface traps located in the gate-to-drain access region

Nonlinear Electronic Transport and Device Performance of HEMTs

Abstract-We assess the impact of nonlinear electronic transport and, in particular, of real space transfer (RST) on device performance for advanced III/V high electron mobility transistors (HEMTs) using the device simulator MINIMOS-NT. In this context, we discuss dc and RF performance issues for pseudomorphic AlGaAs/InGaAs/GaAs HEMTs that are especially relevant for gate-lengths of about 150 nm. All results are compared to and found to be consistent with experimental data for devices processed in two different foundries

Buffer-Related Degradation Aspects of Single and Double-Heterostructure Quantum Well InAlN/GaN High-Electron-Mobility Transistors

We experimentally prove the viability of the concept of the double-heterostructure quantum well InAlN/GaN high-electron-mobility transistor (HEMT) for the device higher robustness and reliability. In the single quantum well InAlN/GaN HEMTs, the intrinsic channel resistance increases by 300% after 1 h off-state stress; much less degradation is observed in the double-heterostructure device with an AlGaN back barrier. Physics-based device simulation proves that the back barrier blocks the rate of carrier injection into the device buffer. However, whatever the quantum well design is, the energy of the injected electrons in the buffer of InAlN/GaN-based HEMTs is higher than that in the buffer of AlGaN/GaN HEMTs. This energy may be sufficient for releasing hydrogen from GaN point defects. (C) 2012 The Japan Society of Applied Physic

Multi-dimensional Modeling and Simulation of Semiconductor Nanophotonic Devices

Self-consistent modeling and multi-dimensional simulation of semiconductor nanophotonic devices is an important tool in the development of future integrated light sources and quantum devices. Simulations can guide important technological decisions by revealing performance bottlenecks in new device concepts, contribute to their understanding and help to theoretically explore their optimization potential. The efficient implementation of multi-dimensional numerical simulations for computer-aided design tasks requires sophisticated numerical methods and modeling techniques. We review recent advances in device-scale modeling of quantum dot based single-photon sources and laser diodes by self-consistently coupling the optical Maxwell equations with semi-classical carrier transport models using semi-classical and fully quantum mechanical descriptions of the optically active region, respectively. For the simulation of realistic devices with complex, multi-dimensional geometries, we have developed a novel hp-adaptive finite element approach for the optical Maxwell equations, using mixed meshes adapted to the multi-scale properties of the photonic structures. For electrically driven devices, we introduced novel discretization and parameter-embedding techniques to solve the drift-diffusion system for strongly degenerate semiconductors at cryogenic temperatures. Our methodical advances are demonstrated on various applications, including vertical-cavity surface-emitting lasers, grating couplers and single-photon sources