Public thesis defense Qi Chen - ICTEAM
sst |
Characterization and Modeling of Low-Frequency Noise in Thin-Film Source-Gated Transistors for Display Applications
Thursday June 11th, 2026 - 3:30pm - Auditorium Mercator 14 - Place Louis Pasteur, 3 - 1348 Louvain-la-Neuve
With the rapid development of advanced displays, flexible electronics, and sensors, thin-film transistors (TFTs) based on low-temperature polycrystalline silicon (LTPS) and amorphous indium gallium zinc oxide (IGZO) have become key devices for modern electronic systems. However, conventional TFT architectures suffer from inherent limitations such as short-channel effects, finite output impedance, and relatively high saturation voltages, which restrict their analog performance and power efficiency. To address these issues, the source-gated transistor (SGT), employing a gate-controlled Schottky source contact, has emerged as a promising alternative for low-power analog applications.
This thesis systematically investigates the low-frequency noise (LFN) characteristics and analog performance of LTPS and IGZO SGTs. Experimental results demonstrate that the LFN of LTPS SGTs is dominated by 1/f noise and cannot be accurately explained by conventional TFT noise models. A dedicated physical LFN model is therefore developed based on thermionic emission and current fluctuations in the reverse-biased Schottky barrier depletion region. By incorporating gate-induced barrier modulation, the model successfully reproduces the measured dependencies on drain and gate voltages. The analysis further reveals that the Schottky barrier noise increases with barrier height and decreases with temperature and gate-source overlap length.
The proposed model is subsequently extended to IGZO SGTs, where good agreement between simulations and measurements confirms the universality of the Schottky-barrier-based LFN mechanism across different semiconductor materials. In addition, the analog figures of merit (FoMs) of LTPS and IGZO devices are comprehensively evaluated using display driver circuits as benchmark platforms. Compared with conventional TFTs, SGTs exhibit significantly lower saturation voltages, improved output stability, and superior power efficiency. In particular, LTPS SGTs achieve extremely low off-state current and very high intrinsic gain owing to their large Early voltage. Although some trade-offs in dynamic response speed are observed, the results demonstrate the strong potential of SGTs for next-generation low-power and high-stability analog driving applications.
Jury members
Prof. Denis Flandre (UCLouvain), Supervisor
Prof. Laurent Francis (UCLouvain), Chairperson
Prof. Jean-Pierre Raskin (UCLouvain), Secretary
Dr. Léopold Van Brandt (UCLouvain)
Prof. Guoli Li (Hunan University, China)
Prof. Radu Sporea (University of Surrey, UK)
Prof. Benjamin Iñiguez Nicolau (Universitat Rovira i Virgili, Spain)