p-Diamond, Si, GaN, and InGaAs TeraFETs
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2020-10-12 |
| Journal | IEEE Transactions on Electron Devices |
| Authors | Yuhui Zhang, M. S. Shur |
| Institutions | Rensselaer Polytechnic Institute |
| Citations | 22 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled āExecutive Summaryā- Superior Material Selection: P-diamond is identified as the optimal material for plasmonic Terahertz (THz) Field Effect Transistors (TeraFETs), outperforming n-diamond, Si, GaN, and InGaAs.
- Resonance Advantage: P-diamondās large effective mass and high carrier mobility yield a long momentum relaxation time (Ļ), allowing the plasmonic resonance condition (ĻpĻ > 1) to be met at exceptionally low frequencies (200 GHz to ~600 GHz).
- Low Critical Mobility: P-diamond TeraFETs require the lowest minimum resonant mobility (Ī¼Ļ ā 700 cm2Ā·V-1s-1) among the tested materials, simplifying the realization of resonant detection.
- Enhanced Sensitivity: Decreasing the operating temperature from 300 K to 77 K significantly improves the detection sensitivity and peak DC response due to the resulting increase in carrier mobility.
- Scaling Performance: When channel length (L) is reduced to 20 nm, the p-diamond TeraFET exhibits the highest DC response across a broad frequency window (up to 6 THz), indicating superior performance at small feature sizes.
- Broad Dynamic Range: The p-diamond detector maintains high detection sensitivity across a large dynamic range at both room temperature and cryogenic temperatures.
Technical Specifications
Section titled āTechnical Specificationsā| Parameter | Value | Unit | Context |
|---|---|---|---|
| P-Diamond Effective Mass (Hole) | 0.63 to 2.12 | m0 | Relative to free electron mass (m0) |
| P-Diamond Mobility (300 K) | 5300 | cm2Ā·V-1s-1 | Maximum reported value used in simulation |
| P-Diamond Mobility (77 K) | 35000 | cm2Ā·V-1s-1 | Maximum reported value used in simulation |
| P-Diamond Momentum Relaxation Time (Ļ) | 10-14 to 10-11 | s | Varies with mobility; highest among tested materials |
| P-Diamond Transition Mobility (Ī¼Ļ) | ~700 | cm2Ā·V-1s-1 | Minimum mobility required for resonant operation |
| P-Diamond Bandgap | ~5.46 | eV | Wide bandgap material |
| P-Diamond Thermal Conductivity | ~23 | W/cmĀ·K | High thermal conductivity |
| P-Diamond Fundamental Resonant Voltage (Uor) | 1.14 | V | At 1 THz, L = 130 nm, n=1 harmonic |
| Target Resonant Frequency Window | 200 to 600 | GHz | Promising range for beyond 5G sub-THz communications |
| Simulated Channel Lengths (L) | 20, 65, 130 | nm | Feature sizes tested for scaling effects |
| Capacitance of Barrier Layer (C) | 0.56 | ĀµF/cm2 | Used in gradual channel approximation (CU = en) |
| Optical Phonon Energy | 165 | meV | Leads to suppression of optical phonon scattering up to ~400 K |
Key Methodologies
Section titled āKey Methodologiesā- Modeling Framework: The study utilized a one-dimensional hydrodynamic model to trace the generation and propagation of plasma waves within the TeraFET channel.
- Simulation Tool: The governing equations (continuity, momentum, and energy transport) were solved using the finite element method within COMSOL 5.4.
- Material Comparison: Simulations were performed on p-diamond, n-diamond, Si, GaN, and InGaAs, using relatively large mobilities close to maximum reported values for each material.
- Device Geometry: Three distinct gated channel lengths (L) were simulated: 20 nm, 65 nm, and 130 nm.
- Thermal Conditions: Device characteristics were evaluated at two primary operating temperatures: Room Temperature (300 K) and Cryogenic Temperature (77 K).
- Boundary Conditions: An ideal open drain condition was applied, where the load resistance (RL) is considered infinite, defined by U(0, t) = U0 + Ua(t) and J(L, t) = 0.
- Resonance Characterization: The ultimate response time (Ļr) was measured by applying an ultra-short (5 x 10-14 s) square-pulse signal to determine the minimum mobility (Ī¼Ļ) required for resonant operation.
- Model Validation: The validity of the hydrodynamic approach was confirmed by verifying that the electron-electron scattering rate (1/Ļee) was always much larger than the inverse momentum relaxation time (1/Ļ) in the simulations.
Commercial Applications
Section titled āCommercial Applicationsā- Beyond 5G/6G Wireless Communications: P-diamond TeraFETs are highly suitable for resonant THz detection in the 240 GHz to 600 GHz bands, crucial for high-speed, sub-THz communication links.
- THz Imaging and Spectroscopy: The high sensitivity and broad dynamic range of p-diamond detectors enable advanced THz imaging systems for security, medical diagnostics, and non-destructive testing.
- High-Speed Optical Pulse Detection: The devices are capable of detecting ultra-short optical pulses, relevant for high-bandwidth data processing and time-domain spectroscopy.
- High-Power and High-Temperature Electronics: Diamondās intrinsic properties (wide bandgap, high thermal conductivity) make it a promising material for RF power devices capable of withstanding large microwave signals and operating at elevated temperatures (up to 350 Ā°C).
- Plasma Wave Electronics: General application in the development of novel plasma-wave-based devices, leveraging the long momentum relaxation time for enhanced performance.
View Original Abstract
p-diamond field effect transistors (FETs) featuring large effective mass,\nlong momentum relaxation time and high carrier mobility are a superb candidate\nfor plasmonic terahertz (THz) applications. Previous studies have shown that\np-diamond plasmonic THz FETs (TeraFETs) could operate in plasmonic resonant\nmode at a low frequency window of 200 GHz to ~600 GHz, thus showing promising\npotential for beyond 5G sub-THz applications. In this work, we explore the\nadvantages of p-diamond transistors over n-diamond, Si, GaN and InGaAs TeraFETs\nand estimate the minimum mobility required for the resonant plasmons. Our\nnumerical simulation shows that the p-diamond TeraFET has a relatively low\nminimum resonant mobility, and thus could enable resonant detection. The\ndiamond response characteristics can be adjusted by changing operating\ntemperature. A decrease of temperature from 300 K to 77 K improves the\ndetection performance of TeraFETs. At both room temperature and 77 K, the\np-diamond TeraFET presents a high detection sensitivity in a large dynamic\nrange. When the channel length is reduced to 20 nm, the p-diamond TeraFET\nexhibits the highest DC response among all types of TeraFETs in a large\nfrequency window.\n