Synergistically Enhanced Performance and Reliability of Abrupt Metal‐Oxide Heterojunction Transistor

Abstract

The large‐area low‐temperature processing capability and versatile characteristics of amorphous oxide semiconductor (AOS) thin‐film transistors (TFTs) are highly expected to promote the developments of next‐generation displays, 3D integrated circuit (3DIC), flexible chips, and electronics. However, the abundant native defects in AOSs engrain an inherent trade‐off between high mobility and trustworthy stability in AOS TFTs, fundamentally limiting the performance metrics and integration scale of oxide‐based electronics. To surmount this obstacle, the bilayer AOS channel is highly expected to combine the merits of diversified AOSs, while the efficiency of such an AOS “heterojunction” is debatable. This work systematically compares the TFTs based on amorphous InGaZnO (a‐IGZO), amorphous InZnO (a‐IZO), and a‐IZO/a‐IGZO bilayer. The active cation interaction between metal‐oxide semiconductors gives rise to a mixed AOS layer rather than a heterojunction channel, corresponding to moderate performance metrics. Such a spontaneous cation interdiffusion is effectively prevented using a dense metal‐oxide dielectric interlayer, aluminum oxide (AlOx). The sharpened interface effectively forms an abrupt metal‐oxide heterojunction, while the electron can still tunnel through the ultrathin AlOx to create a quantum well of 2D electron gas (2DEG). The overall performance and reliability of multilayer AOS TFT are synergistically enhanced using the proposed abrupt metal‐oxide heterojunction architecture.

Ultra-thin gate insulator of atomic-layer-deposited AlO x and HfO x for amorphous InGaZnO thin-film transistors

“…A larger N it for HfO x -gated TFTs indicates a larger number of trap defects in the HfO x insulators and at the HfO x /a-IGZO interface, consistent with the greater frequency dispersion in figure 1(e). Generally, the defect at the AOS/GI interface might be introduced by interficial reaction [19,20], diffusion [27], or strain [28,29]. As reported, the ALD process of high-k dielectric with chemically reactive species often induces abundant defect states at the GI/channel interface and in the AOS channel [19,30].…”

Mechanistic Study of the Influence of Reactant Type and Addition Sequence on the Microscopic Morphology of α-Al2O3

“…Compared to β-alumina and γ-alumina, α-alumina has the tightest crystal structure, highest chemical stability, and excellent electrochemical properties and corrosion resistance. It is widely used in areas such as integrated circuits [1,2], optical sensing [3,4], filler materials [5], and refractory materials [6,7]. The importance of the microstructure on the application performance of materials is well known.…”

Performance Improvement of In-Ga-Zn Oxide Thin-Film Transistors by Excimer Laser Annealing

“…In recent decades, amorphous metal-oxide semiconductor (AOS) thin-film transistors (TFTs) have attracted extensive attention. Among them, a-InGaZnO (a-IGZO) TFTs are highly favored because they exhibit higher carrier mobility than amorphous silicon TFTs, lower fabricated temperature and better large-area uniformity than those of poly-silicon TFTs, ultralow off-state current, and a steep subthreshold slope [1][2][3][4][5]. With the development of advanced applications, current-driven displays, and back-end-of-line devices, there is a need for AOS TFTs with much higher mobility.…”