Integration of Quantum Dot Light-Emitting Diodes and Charge Trap Thin-Film Transistor Arrays for Memory-In-Pixel...

Area of Science:

• Materials Science
• Electrical Engineering
• Optoelectronics

Background:

• Ultrahigh-resolution displays and extended reality (XR) demand compact, low-power pixel architectures for integrated memory and light emission.
• Charge-trap thin-film transistors (CTTFTs) using oxide semiconductors are promising for nonvolatile memory due to performance and fabrication compatibility.
• Existing solutions often lack integrated memory and light-emission functionalities at the pixel level, necessitating novel device designs.

Purpose of the Study:

• To propose and demonstrate a novel memory-in-pixel (MIP) device monolithically integrating a CTTFT and a quantum dot light-emitting diode (QD-LED).
• To achieve self-erasing functionality within a single pixel for enhanced display performance and reduced complexity.
• To evaluate the electrical and optical performance of the integrated MIP device, including CTTFT characteristics and QD-LED efficiency.

Main Methods:

• Fabrication of a CTTFT using an Al2O3/HfO2/Al2O3 gate dielectric and an oxide semiconductor channel.
• Monolithic integration of a QD-LED atop the CTTFT using a photolithography-based lift-off process to enable self-erasing functionality.
• Characterization of CTTFT performance (mobility, subthreshold swing, on/off ratio, memory window) and QD-LED performance (external quantum efficiency - EQE, erasing efficiency).

Main Results:

• The CTTFT exhibited high field-effect mobility (22.1 cm2/V·s), a sharp subthreshold swing (99.1 mV/dec), an on/off ratio >10^9, and a wide memory window (6.06 V).
• Monolithically integrated QD-LEDs achieved significant EQEs: 20.9% (red), 6.5% (green), and 1.7% (blue).
• Cd-free ZnSeTe QD-LEDs demonstrated a notable erasing efficiency of ~60%, surpassing Cd-based counterparts and enabling self-erasing MIP operation.

Conclusions:

• The developed hybrid MIP architecture successfully integrates CTTFT memory and QD-LED emission functions within a single pixel.
• The self-erasing MIP device operates without external erase components, offering a compact and efficient solution for next-generation displays.
• This environmentally friendly platform, particularly with Cd-free QDs, is suitable for advanced, high-resolution display applications demanding integrated functionalities.