13.2: Invited Paper: LTPS vs Oxide Backplanes for AMOLED Displays: System Design Considerations and Compensation Techniques

Abstract

The two major backplane technologies for AMOLED displays are LTPS and oxides. Despite their similarities, the differences are significant requiring intricate design considerations and compensation techniques to achieve good display uniformity and lifetime while eliminating second order effects associated with IR drop, ground bouncing, and parasitic capacitance. This paper presents a study in contrasts between LTPS and oxide backplane technologies from the standpoint of system design and compensation techniques.

Recent progress in OLED and flexible displays and their potential for application to aerospace and military display systems

“…While both LTPS and AOS TFTs offer significantly higher mobilities compared to a-Si:H, AOS TFT has the lowest offcurrent even when compared to a-Si:H as shown in Figure 1 [1][2][3][4]. A major reason for the lower leakage current of the unipolar IGZO semiconductor TFT is due to its wider band gap (E G (IZGO) = 3.25 eV), compared to the narrower band gaps of a-Si:H and LTPS semiconductors (E G (a-Si:H) = 1.7 eV and EG (LTPS) = 1.1 eV) that are bipolar.…”

“…Today advanced LTPS TFT backplanes are used almost exclusively for the high resolution smart phone displays and tablet PC displays using both OLED as well as LCD display media. Another option that became available recently for the backplane is amorphous oxide semiconductor (AOS) TFTs [1,2]. Major advances have been made in the AOS TFT technologies during the past couple of years and its commercialization has already started for manufacturing AM OLED and then AM LCD as well.…”

58.4: A 31‐inch 4K2K WRGB AMOLED TV with High‐Stability IGZO Back Plane

“…However, as OLED is a current-driving device, commercially used amorphous silicon (a-Si) thin film transistor (TFT) backplanes with low mobility could not be compatible with OLED. Furthermore, low-temperature polycrystalline silicon (LTPS) TFT backplanes have the high mobility to drive OLED, but the lower uniformity caused by grain boundaries restrains its use in OLED without employing complex compensation circuits [3]. Moreover, LTPS may consume a large amount of power when displaying a still image due to high off-current and its fabrication process is complicated which will cause high cost.…”

8.2: Invited Paper: Elevated‐Metal Metal‐Oxide Thin‐Film Transistor with Self‐Aligned Source/Drain Regions

“…Due to the requirement of finite alignment margins, an inevitable overlap exists between the gate electrode and the S/D regions or electrodes of a commonly deployed [2] bottom-gate, staggered thin-film transistor (TFT). The resulting overlap capacitance [3] contributes to a larger . Such parasitic capacitance can be reduced by employing a TFT with the edges (junctions) of the S/D regions self-aligned to those of the gate electrode.…”