Tsukasa Eguchi

Dependence of polycrystalline silicon thin-film transistor characteristics on the grain-boundary location

Dependence of transistor characteristics on the grain-boundary location in polycrystalline silicon (poly-Si) thin-film transistors (TFTs) has been analyzed using device simulation. In the linear region, degradation is similar wherever the grain boundary is located. On the other hand, in the saturation region, degradation is less when the grain boundary is in the pinch-off region near the drain edge and degradation is similar when the grain boundary is elsewhere. Although this dependence is similar to the dependence on the trap location in single-crystal silicon transistors, the mechanism is different. This dependence in poly-Si TFTs is because the coulombic potential barrier caused by the grain boundary is lowered in the high electric field in the pinch-off region. This is a kind of Poole–Frenkel effect.

55.2: Integrated Active Matrix Capacitive Sensors for Touch Panel LTPS-TFT LCDs

We have developed active matrix capacitive sensors for detecting touch events in low-temperature polycrystalline silicon (LTPS) TFT LCDs with Fringe-Field Switching (FFS) technology. These sensors enable touch events to be detected regardless of ambient light and enable touch events to be input simultaneously at 3 or more points.

24.2: A 1300-dpi Optical Image Sensor Using an a-Si:H Photo Diode Array Driven by LTPS TFTs

We have developed a 1300-dpi optical image sensor using a hydrogenated amorphous silicon (a-Si:H) pin diode array driven by low-temperature polycrystalline silicon (LTPS) thin film transistors (TFT) on a glass substrate. This paper describes a new architecture for achieving a high-resolution optical image sensor using LTPS TFT production equipment.

Device Simulation of Grain Boundaries with Oxide-Silicon Interface Roughness in Laser-Crystallized Polycrystalline Silicon Thin-Film Transistors

For laser-crystallized polycrystalline silicon thin-film transistors, the effect of grain boundaries with oxide-silicon interface roughness on the transistor characteristics has been analyzed using device simulation. When grain boundaries and interface roughness are considered simultaneously, degradation of the on-current caused by grain boundaries is reduced by the interface roughness because the electric field concentration increases the carrier density and improves the conductance.

Active‐matrix sensor in AMLCD detecting liquid‐crystal capacitance with LTPS‐TFT technology

— An active-matrix capacitive sensor for use in AMLCDs as an in-cell touch screen has been developed. Pixel sensor circuits are embedded in each pixel by using low-temperature polycrystalline-silicon (LTPS) TFT technology. It detects a change in the liquid-crystal capacitance when it is touched. It is thin, light weight, highly sensitive, and detects three or more touch events simultaneously.