Tailoring Subthreshold Swing in A-IGZO Thin-Film Transistors for Amoled Displays: Impact of Conversion Mechanism on Peald Deposition Sequences

Breaking the Trade-Off Between Mobility and On-Off Ratio in Oxide Transistors

Amorphous oxide semiconductors (AOS) are pivotal for next-generation electronics due to their high electron mobility and excellent optical properties. However, In2O3, a key material in this family, encounters significant challenges in balancing high mobility and effective switching as its thickness is scaled down to nanometer dimensions. The high electron density in ultra-thin In2O3 hinders its ability to turn off effectively, leading to a critical trade-off between mobility and the on-current (Ion)/off-current (Ioff) ratio. This study introduces a mild CF4 plasma doping technique that effectively reduces electron density in 10 nm In2O3 at a low processing temperature of 70 °C, achieving a high mobility of 104 cm2 V⁻¹ s⁻¹ and an Ion/Ioff ratio exceeding 10⁸. A subsequent low-temperature post-annealing further improves the critical reliability and stability of CF4-doped In2O3 without raising the thermal budget, making this technique suitable for monolithic three-dimensional (3D) integration. Additionally, its application is demonstrated in In2O3 depletion-load inverters, highlighting its potential for advanced logic circuits and broader electronic and optoelectronic applications.

Design of an Atomic Layer-Deposited In2O3/Ga2O3 Channel Structure for High-Performance Thin-Film Transistors

For potential application in advanced memory devices such as dynamic random-access memory (DRAM) or NAND flash, nanolaminated indium oxide (In-O) and gallium oxide (Ga-O) films with five different vertical cation distributions were grown and investigated by using a plasma-enhanced atomic layer deposition (PEALD) process. Specifically, this study provides an in-depth examination of how the control of individual layer thicknesses in the nanolaminated (NL) IGO structure impacts not only the physical and chemical properties of the thin film but also the overall device performance. To eliminate the influence of the cation composition ratio and overall thickness on the IGO thin film, these parameters were held constant across all conditions. Thin-film transistors (TFTs) with a homogeneous In0.72Ga0.29Ox channel layer (referred to as IGO18) exhibited a reasonable field-effect mobility (μFE) of 58.1 cm2/(V s) and ION/OFF ratio of >108. A significant improvement (∼94.1 cm2/(V s)) in μFE was observed for TFTs with an In2O3/Ga2O3 heterojunction stack (referred to as IGO1). Because the channel layers of both devices had an identical average cation composition and physical thickness, the superior performance of the latter can be attributed to the emergence of a quasi-two-dimensional electron gas (2DEG) and the attainment of high-quality crystallinity. This study underscores the criticality of supercycle duty design to prevent cation intermixing, enabling the exploitation of the 2DEG effect in high-performance oxide TFTs for memory device applications.

Solution-Processed Metal Oxide Thin-Film Transistor at Low Temperature via A Combination Strategy of H2O2-Inducement Technique and Infrared Irradiation Annealing

Solution processing has emerged as a promising technique for the fabrication of oxide thin-film transistors (TFTs), offering advantages such as low cost, high throughput, and exceptional compositional control. However, achieving reasonable electrical properties typically demands high annealing temperatures in the fabrication process. In addressing this challenge, a novel combination strategy is proposed that involves integrating the H2O2 inducement technique with infrared (IR) irradiation annealing. The study investigates the effects of precursors and IR irradiation annealing temperatures on the electrical properties of In2O3 TFTs. It is found that H2O2 can help accelerate the decomposition of organic residues, while IR irradiation annealing could enhance the film densification. By employing the proposed strategy, metal oxide TFTs consisting of a Zr-Al-O dielectric fabricated at 230 °C and an In2O3 channel layer fabricated at 185 °C demonstrated high performance with field-effect mobility = 31.7 cm2 V-1·s-1, threshold voltage = 1.3 V, subthreshold swing = 0.13 V per decade, and on-to-off current ratio = 1.1 × 105. This work demonstrates the proposed combinational strategy is a general method to fabricate not only metal oxide semiconductors but also dielectrics.