Oxide Thin-Film Transistor-Based Vertically Stacked Complementary Inverter for Logic and Photo-Sensor Operations

Area of Science:

• Materials Science
• Electronics Engineering
• Semiconductor Physics

Background:

• Traditional 2D planar complementary logic circuits face limitations in dimension and parasitic resistance.
• Oxide thin-film transistors (TFTs) offer potential for advanced electronic applications.

Purpose of the Study:

• To demonstrate a vertically stacked 3D complementary inverter using oxide TFTs.
• To overcome the fundamental limits of 2D planar complementary logic circuits.
• To explore the photoresponse characteristics of the novel device structure.

Main Methods:

• Fabrication of a vertically stacked complementary inverter with a bottom-gate p-channel tin monoxide (SnO) TFT on a top-gate n-channel indium-gallium-zinc oxide (IGZO) TFT.
• Utilizing a shared common gate electrode for both TFTs.
• Characterization of the inverter's electrical performance, including voltage gain and noise margins.
• Evaluation of the device's visible-light photoresponse.

Main Results:

• The fabricated vertically stacked complementary inverter achieved full swing characteristics.
• A high voltage gain of approximately 33.6 was obtained at a supplied voltage of 10 V.
• Excellent noise margins (high: 3.13 V, low: 3.16 V) were demonstrated.
• The inverter exhibited significant visible-light photoresponse, indicating potential for photo-sensing.

Conclusions:

• The vertically stacked 3D complementary inverter design effectively overcomes the limitations of 2D structures.
• The SnO/IGZO complementary inverter demonstrates superior performance compared to previous oxide TFT-based designs.
• The device shows promise as a sensitive photo-sensor for visible light detection using a voltage read-out scheme.