Laser-recrystallized polycrystalline-silicon thin-film transistors with low leakage current and high switching ratio

Abstract

Laser-recrystallized polycrystalline-silicon thin-film transistors (poly-5i TFT's) with offset-gate structures have been fpbricated on quartz substrates. Offset-gate structures make it possible to reduce leakage currents to as low as 5 X A/pm at V, = 10 V, more than two orders of magnitude lower than that in conventional-structure poly-Si TFT's. Optimization of the dopant concentration in offset-gate regions minimizes degradation of drive current, enabling high switching ratios exceeding lo8. Calculations based on the quasi-two-dimensional model indicate that the reduction in leakage current is due to a decrease in lateral electric field strength in the drain depletion region.

50.3: Novel Self‐Aligned LDD/Offset Structure for poly‐Si Thin Film Transistors

“…It was reported that the leakage current in the poly-Si TFTs is mainly attributed to thermionic field emission due to the trap states in the region between channel and drain [1]. To reduce the leakage current, there have been suggested two approaches; i) hydrogen passivation to reduce the trap state density in the poly-Si layer [2] and ii) formation of lightly doped drain (LDD) structure to optimize the conventional TFT structure by decreasing electric field at the depletion region [3]. In particular, LDD/offset TFT structures typically require processes with additional photo-lithography steps, which can be disadvantageous in term of yield and cost.…”

Active‐matrix organic light‐emitting diode using inverse‐staggered poly‐Si TFTs with a center‐offset gated structure

“…Various lightly doped drain (LDD) and offset gated structures have been adopted to suppress the leakage currents by reducing electric field near the drain electrode. 6 However, the ON-currents of LDD and offset TFTs are less than those of self-aligned TFTs due to the high series resistance of the offset (LDD) region if it is longer, and also an additional process step is needed to make the LDD region. 7 In this paper, we studied the fabrication of a 2.2-in.…”

9.3: Active‐Matrix Organic Light Emitting Diode Using Inverse Staggered Poly‐Si TFT with a Center‐Offset Gated Structure

“…This is a serious problem for pixel switches in AMOLED. Various lightly doped drain (LDD) and offset gated structures have been proposed to suppress the leakage currents by reducing the electric field near drain [5]. However, the ON currents of LDD and offset TFTs are much less than those of coplanar TFT due to the high series resistance of the offset (LDD) region [6].…”