Robust Gate Driver on Array Based on Amorphous IGZO Thin-Film Transistor for Large Size High-Resolution Liquid Crystal Displays

Abstract

Amorphous IGZO thin-film transistors (TFTs) in an etch stop layer (ESL) structure was processed on 2500 mm × 2200 mm size substrate. The fabricated devices exhibit enhancement mode characteristics, and excellent uniformity over large area. The presented good operational stabilities under both positive gate bias temperature stress (PBTS) and negative gate bias temperature stress (NBTS) tests can well meet the requirements for pixel switching. However, considering even threshold voltage shift under long term positive bias stress might affect proper operation of the gate driver on array (GOA), a design with a pulse gating scheme is proposed, consisting of 13 TFTs and 1 capacitor, to avoid long term continuous bias stressing of the TFT. With the proposed GOA design, a 32-inch QUHD (7680×4320) highresolution liquid crystal display (LCD) panel with a 7 mm wide bezel is achieved. The reliability of the GOA circuit is well proved through standard aging tests.

P‐15: Student Poster: Reliable Gate Driver for Real‐Time External Compensated AMOLED Display Using InGaZnO TFTs

“…In P4 period, V SESTV and V SEVDD change from low to high, T404 and T405 are turned on, so the charge storage node M of the inter-frame storage structure is bootstrapped to a higher level. Besides, V QC and V QS are charged to high level, the relationship can be expressed as equation ( 1) and (2). Due to the low level of V SECK3 and V SCCK3 , VSCANn and VSENSEn still remain at VSS0.…”

“…[1]. For large-size AMOLED displays, the main backplane technology is a-InGaZnO TFT, this is because a-InGaZnO TFT has advantages of high mobility, good stability, low cost, and excellent uniformity over large fabrication areas [2] [3]. However, compensation functions are still required to suppress display non-uniformities as there are inevitable characteristics variations among display pixels after long-term stress.…”

P‐1.5: Dynamic Current Stress‐Induced Instabilities of a‐InGaZnO TFTs

“…Amorphous oxide semiconductor (AOS) thin-film transistors (TFTs), such as a-InGaZnO (a-IGZO) TFT, have attracted extensive attention, due to high mobility, lowfabrication temperature and excellent uniformity [1]. Recently, the large current-driving capability of AOS TFTs have been increasingly demanded by various applications, such as gate-driver-on-array (GOA) circuits [2] and TFT backplanes for Micro-LED displays [3]. The AOS TFTs are well known to degrade under various gate-bias stresses, as represented by the positive and /or negative threshold voltage (Vth) shifts (ΔVth) under positive bias temperature stress (PBTS) [4] and negative bias illumination stress (NBIS) [5].…”

Supercritical Ammoniation-Enabled Interfacial Polarization for Function-Mode Transformation and Overall Optimization of Thin-Film Transistors

“…Thin-film transistors (TFTs) are becoming increasingly important due to their promising development potential and broad market in the high-end panel and flexible display. − Amorphous indium gallium zinc oxide (a-IGZO), out of diverse metal oxides, draws wide attention in the areas of TFTs. A-IGZO TFTs exhibit high optical transparency, high carrier mobility, and excellent uniformity, making it one of the most competitive candidates. − Although the manufacturing process of a-IGZO TFTs is relatively mature, lack of appropriate technology in realizing depletion-mode (DM) a-IGZO TFTs still limits the implementation of complementary-type circuits. Whereas, circuits constructed with single-type TFTs will consume relatively high power. − An effective method to address this predicament and facilitate the power reduction is to implement DM and enhancement-mode (EM) TFTs in the circuit-level design. − Heretofore, several approaches to acquire DM a-IGZO TFTs have been studied, including modulating the thickness of materials, anodic oxidation, employing different back-channel capping layers, or fluorination treatment. − Nevertheless, these techniques incur a significant increase in process complexity and the relatively high-temperature treatment may also affect device performance.…”