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Electrical characteristic analysis using low-frequency noise in low-temperature polysilicon thin film transistors
1Department of Electronics Engineering, Chungnam National University, Daejeon, 305-764, Korea.
Journal of Nanoscience and Nanotechnology
|September 13, 2012
Summary
Investigating low-frequency noise (LFN) in thin film transistors reveals that thinner active layers (40 nm) exhibit superior electrical properties compared to thicker ones (80 nm). This is attributed to reduced trap density and coulomb scattering at interfaces.
Area of Science:
- Materials Science
- Electrical Engineering
- Semiconductor Physics
Background:
- Low-temperature polysilicon thin film transistors (LTPS TFTs) are crucial for display technologies.
- Understanding electrical degradation mechanisms in LTPS TFTs is essential for device performance improvement.
- Active layer thickness is a key parameter influencing LTPS TFT characteristics.
Purpose of the Study:
- To analyze the electrical characteristics of p-type LTPS TFTs with varying active layer thicknesses (40 nm and 80 nm) using low-frequency noise (LFN).
- To investigate the impact of active layer thickness on carrier transport and defect-related scattering mechanisms.
- To correlate LFN measurements with interface trap densities for explaining device performance variations.
Main Methods:
- Electrical characteristic analysis, including transfer curves.
- Low-frequency noise (LFN) measurements and modeling.
- Carrier number fluctuation and correlated mobility fluctuation models.
- Extraction of trap densities at grain boundaries using established methods (Proano et al., Levinson et al.).
Main Results:
- The 40-nm LTPS TFT demonstrated superior electrical characteristics compared to the 80-nm device.
- LFN analysis effectively modeled carrier number fluctuations in both devices.
- The 40-nm device exhibited lower trap density and coulomb scattering than the 80-nm device.
- Coulomb scattering significantly impacts devices with inferior electrical properties.
Conclusions:
- Interface traps between the active layer and gate insulator are a primary cause of electrical degradation in LTPS TFTs.
- LFN analysis provides a quantitative method to assess trap densities and understand scattering mechanisms.
- Optimizing active layer thickness is critical for enhancing the performance and reliability of LTPS TFTs.
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