Emerging Horizons in TCAD
Knowledge-Guided Neural Network Based Nonlinear Current Model With Combined Loss Function
Presenter: Junjun Qi, Xidian University
- Abstract: A knowledge-guided Neural network (KGNN)-based nonlinear current model of InP heterojunction bipolar transistor (HBT) is proposed. To improve modeling accuracy and consistency, a combined loss function is constructed and modeling consistency checks are implemented during the training of the neural network to penalize violations of the physical laws. The accuracy of the developed nonlinear current model was verified by comparing the measured and simulated pulse IV results.
Physical Insight into Single-Event Upsets of DICE Circuits and Hardening Strategy
Presenter: Yutao Chen, Sun Yat-sen University
- Abstract: The single-event upset (SEU) effects, caused by ionizing radiation, poses a significant challenge to the reliability of integrated circuits. In this work, we investigate SEU in dual interlocked storage cell (DICE) circuits for the underlying physical mechanisms and mitigating its impact. SEU in DICE circuits is primarily caused by two factors: data pattern and charge sharing. Data pattern is closely related to the signal transmission of the circuits, while charge sharing arises from the diffusion motion of carriers induced by radiation. A novel circuit hardening strategy based on split active area (SAA) is developed, which aims to reduce the susceptibility to single-event upsets. The effectiveness of the SAA scheme is evaluated through TCAD simulations. The results demonstrate that the proposed SAA optimization effectively decreases the occurrence of SEU in DICE circuits, thereby enhancing the overall reliability against radiation.
Simulation Study of Gate-All-Around TFET Based on Polarization Effect
Presenter: Zhen Dou, Xi'an University of Posts and Telecommunications
- Abstract: The potential of Tunnel Field-Effect Transistors (TFETs) in overcoming the limitation of the 60 mV/dec subthreshold swing has attracted considerable attention. This paper proposes a gate-all-around TFET based on polarization effects, termed Gate-all-around-Polar-TFET (GAA-P-TFET), to further optimize the performance of TFETs, including reducing the subthreshold swing (SS) and improving the on/off current ratio ION/IOFF. After simulation analysis using Sentaurus TCAD, the SS of GAA-P-TFET can be reduced to as low as 6.7 mV/decade at a drain voltage of 0.5 V, and the highest order of magnitude of the on/off current ratio can reach to 12.
A New Framework to MOS Device for Cryogenic Application: Linking Materials with Modeling
Presenter: Chenyang Zhang, Shanghai Jiao Tong University
- Abstract: We proposed a novel framework that links the channel material property with the MOS device physical model for their cryogenic application. Due to subthreshold swing saturation and current inflection phenomenon at cryogenic temperature, the physical model for the band tail state of cryogenic MOSFET has gained widespread recognition and application, demonstrating a strong correlation with experimental outcomes. Despite the broad acceptance and empirical success of this model, its reliance on a simplified DOS model introduces potential inaccuracies in the extraction of band tail state parameters, and limits its applicability to other channel materials. Here, we propose and implement, for the first time, the calculation of DOS using DFT rather than the simplified 2-dimensional electron gas (2DEG) model. Our results not only align with those derived from simplified models but also extend their application to other alternative channel materials (like SiGe) and provide simulation predictions. This advancement marks a significant leap forward in screening optimal channel materials for use at cryogenic temperatures, potentially revolutionizing the design and performance of MOSFETs in cryogenic applications.
Simulation of MEMS Microfabrication Process Based on Narrow Band Level Set and Ray Tracing Methods
Presenter: Binbin Zheng, Southeast University
- Abstract: To improve the efficiency of MEMS device design and development, a MEMS process simulation program has been developed. In this paper, an evolutionary algorithm for surface contours, narrow band level set method, is introduced. The surface rate of the machined material is calculated by the process physics model and the ray tracing method. The surface rate and evolution algorithm are coupled to simulate the morphology evolution of the process. The simulation program is written in C++ language, and the most time-consuming part of the program is accelerated in parallel.
Graded Composition Double Quantum Dots: Nucleation Features, Characterization and Application for New Generation Nano-Optoelectronic Devices
Invited Speaker: Karen Gambaryan, Yerevan State University
The nucleation process, characterization and possible applications of GCQDs and QDMs grown from In-As-Sb-P composition liquid phase using Stranski–Krastanow growth mode are presented. AFM investigations show that the massive of QD-structures grown on an InAs(100) surface mainly consists of single conical GCQDs, as well as laterally double, triple, quadruple and quintuple QDMs (Fig. 1). Surface concentration of QDMs was up to two order lower than that of single QDs. QDs growth process was stopped at the initial stage of Ostwald ripening and coalescence to overcome further coarsening.Characterization shows that the QDs average diameter to height ratio equals to ~9, surface density ranges from 5 to 8×109 cm-2 with heights and diameters from 5 nm to 25 nm and 20 nm to 140 nm, respectively.Gauss-like distribution on the dependence of QDs number versus both average diameter and height was observed.
The experimental and quantitative studies of uncapped In(As,Sb,P) double quantum dots (DQDs),suited for application in novel resonant tunneling nanodiods or single-photon nanooptical up- and downconverters in the mid-infrared spectral range are presented. Details on the growth process using epitaxy from the quaternary liquid phase, as well as the characterization using atomic force microscopy and scanning electron microscopy are presented. We find that most type-II DQDs exhibit an asymmetry such that the two QDs of each pair have different dimensions, giving rise to correspondingly different quantum confinement of hole states (in our material system) localized in each QD. Based on these data, we have performed simulations to identify the relationship between QD dimensions and the energy difference between corresponding confined hole states in the two QDs. Finally, we have determined the strength of an applied electric field required to energetically align the hole ground states of two QDs of different dimensions in order to facilitate hole tunneling. QDs massive optical properties measurements show the enlargement of absorption spectra to long (up to ~3.8 μm) wavelength region at room temperature.Additionally, an idea of DQDs application in new generation opto-electronic devices will be presented.