Analysis and characterization of the GaAs MOSFET with High-k gate dielectric material and also do the small signal analysis and noise analysis using TCAD tool. In present research work GaAs is employed as substrate material. Band gap of GaAs is about 1.43eV. Lattice constant for GaAS is 5.65A. Substrate doping is 1x10^16 cm-3. HFO2 gate dielectric deposited on GaAs(100) substrate. HFO2 film is 20nm thick. Dielectric constant of HFO2 is order of 20-25. Permittivity (F cm^-2) is 20€0. Band gap (eV) is 4.5-6.0.HFO2 grown by Atomic Layer Deposition on GaAs. The transition metal Au is proposed dopant for GaAs. Source/Drain junction depth is 20nm. Doping levels of drain source are 1e20. Gold is used for gate metal. A working GaAs device is simulated and out performs the Si core device due to its increased mobility. It also decreases leakage current. Solve the problem of Fermi level pinning. So GaAs MOSFET is always better than Si MOSFET.
Table of Contents
1. INTRODUCTION
1.1 Basic MOS capacitance structure
1.2 GaAs used as substrate
2. Introduction to silvaco tcad tool
2.1 Process Simulator-ATHENA
2.3 Device Simulator-ATLAS
2.3.1 Inputs and Outputs of Atlas
3. Problem formulation
4. Contributory work (Part-I)
4.1 MOS Capacitor
5. Contributory work (part-II)
5.1 Id-Vd Characteristics for Lg=1µm of Si MOSFET
5.2 Id-Vg for Si MOSFET
5.3 Id-Vg Characteristics for Lg=1µm
5.4 Id-Vd Characteristics for Lg=1µm of GaAs MOSFET
5.5 Id-Vg Characteristics of GaAs MOSFET
5.6 Id-Vg Characteristics for Lg=1µm
5.6.1 Y- Parameter of GaAs MOSFET
5.6.2 S-Parameter of GaAs MOSFET
6. Results and discussion
7. Conclusion
Research Objectives & Topics
This work aims to conduct an analysis and characterization of GaAs MOSFETs utilizing high-k gate dielectric materials, specifically performing small signal and noise analysis via the TCAD simulation tool to demonstrate performance advantages over traditional silicon-based devices.
- Analysis of GaAs as a high-mobility semiconductor substrate material.
- Implementation of HfO2 as a high-k gate dielectric to mitigate leakage current.
- Comparative simulation of GaAs and Si MOSFET device characteristics.
- Utilization of Silvaco TCAD (ATHENA and ATLAS) for semiconductor process and device modeling.
- Evaluation of electrical performance metrics, including drain current and capacitance characteristics.
Excerpt from the Book
1. INTRODUCTION
Metal-Oxide-Semiconductor (MOS) capacitors are the heart of every digital circuit such as single memory chip, dynamic random-access memory (DRAM), switched capacitor circuits, analog-to-digital converters and filters, optical sensors and solar cells. A schematic view of a MOS capacitor is shown in the Fig.1.The MOS capacitor is parallel plate capacitor with silicon (S) as one electrode and the metal (M) as the other electrode. The insulator is generally an oxide (O) layer of silicon. The metal electrode is also known as the gate of the system. The silicon has an ohmic contact to provide an external electric contact. The thickness of the insulator (oxide) layer is denoted by d, and it determines the capacitance of the MOS capacitor. VG is the voltage applied to the gate of the MOS capacitors.
Compound III-V materials are attractive for achieving enhanced n-FET mobility, due to their high bulk electron mobility. III-V channel n-MOSFETs can achieve performance enhancement as well as reduced dynamic power consumption for a fixed performance level. Si CMOS technology has been driven by device scaling to increase performance, as well as reduce cost and maintain low power consumption. However, as devices are scaled below the 100nm region, performance gain has become increasingly difficult to obtain by traditional scaling. High mobility materials can greatly improve the power performance tradeoff which is a tremendous advantage for VLSI digital applications. Currently in industry, mobility enhancement is achieved by applying strain to conventional Si MOSFETs, either through process induced strain or substrate engineering. However, the mobility benefits that can be achieved by staining Si are limited and reduced by scaling, and there is great interest in studying non-Si channel materials to achieve even higher motilities. For gate materials, traditional SiO2 is being replaced by High-k dielectric to reduce the gate leakage current.
Summary of Chapters
1. INTRODUCTION: Outlines the fundamentals of MOS capacitor structures and discusses the motivation for using III-V compound semiconductors and high-k dielectrics in modern device fabrication.
2. Introduction to silvaco tcad tool: Describes the software framework used for modeling, covering the process simulation capabilities of ATHENA and the device simulation features of ATLAS.
3. Problem formulation: Specifies the technical parameters and materials for the GaAs MOSFET research, including doping levels, dielectric thickness, and junction depths.
4. Contributory work (Part-I): Details the configuration and structural specifications for the formation of the MOS capacitor within the TCAD environment.
5. Contributory work (part-II): Presents the comprehensive simulation results for both Si and GaAs MOSFETs, covering DC output characteristics, Id-Vd/Id-Vg curves, and frequency-dependent parameters.
6. Results and discussion: Compares the electrical performance of GaAs and Si MOSFETs, confirming the superior performance of the GaAs-based architecture.
7. Conclusion: Summarizes the findings, highlighting the increased mobility and reduced leakage current of the simulated GaAs device compared to silicon alternatives.
Keywords
GaAs MOSFET, TCAD, HfO2 Gate, Semiconductor, High-k Dielectric, Electron Mobility, Device Simulation, ATLAS, ATHENA, MOS Capacitor, VLSI, Silicon, Leakage Current, Band Gap, Substrate Engineering.
Frequently Asked Questions
What is the core subject of this research?
The research focuses on the simulation, analysis, and characterization of GaAs-based MOSFETs that integrate high-k dielectric materials to enhance performance.
What are the primary thematic areas covered?
The main themes include semiconductor material properties, MOSFET scaling challenges, the application of high-k gate dielectrics, and the use of TCAD software for device simulation.
What is the primary goal of this study?
The primary goal is to demonstrate that a GaAs MOSFET, when engineered with high-k dielectrics, outperforms traditional Silicon MOSFETs in terms of electron mobility and leakage current reduction.
Which scientific methods were employed?
The research utilized computational simulation methodologies, specifically employing Silvaco's ATHENA for process simulation and ATLAS for analyzing the electrical behavior of the semiconductor structures.
What does the main body of the work address?
The main body addresses the structural design of MOS capacitors, the comparative analysis of GaAs and Si substrates, and the detailed extraction of Id-Vd and Id-Vg characteristics through numerical simulation.
How can this work be categorized via keywords?
The work is categorized by keywords such as GaAs MOSFET, TCAD, HfO2 Gate, High-k Dielectric, and Electron Mobility, reflecting its focus on advanced semiconductor device physics.
How does the usage of HfO2 influence the device?
HfO2 is utilized as a high-k dielectric to reduce gate leakage current while allowing for continued device scaling, which is difficult to achieve with traditional SiO2 layers.
Why is GaAs considered a better substrate than Silicon in this research?
GaAs provides superior electron transport properties and higher mobility compared to Silicon, making it a more efficient material for high-performance digital applications.
What role does the ATLAS simulation tool play?
ATLAS is used to predict the electrical behavior of the specified semiconductor structure, providing insight into the internal physical mechanisms associated with the device's operation under various bias conditions.
What is the significance of the "Fermi level pinning" mention?
The study highlights that the proposed GaAs MOSFET design helps solve the common problem of Fermi level pinning, which is a critical step in ensuring the reliability and performance of GaAs-based transistors.
- Quote paper
- Krupal Pawar (Author), Vasudha Patil (Author), 2015, Analysis and Characterization of GaAs MOSFET with High-K Dielectric Material, Munich, GRIN Verlag, https://www.grin.com/document/289225
