Effect of Moisture Exchange Caused by Low‐Temperature Annealing on Device Characteristics and Instability in InSnZnO Thin‐Film Transistors

Abstract

Thin‐film transistors (TFTs) in practical operations are inevitably impacted by moisture and temperature. An investigation on the joint effect of environmental moisture and working temperature on device characteristics and instability is becoming necessary. However, few related studies have been performed. In this work, a low‐temperature (LT) annealing in air is proposed to simulate the working conditions of TFTs in display applications. The effect of moisture exchange caused by LT annealing on device characteristics and instability of InSnZnO (ITZO) TFTs is systematically investigated. Combined with X‐ray photoelectron spectroscopy analysis, TCAD design simulation, and the measurement of relative humidity (RH) change on the device surface, a model considering water diffusion and water ionization is proposed. The negative shift of the transfer curve is attributed to the extra electrons released from the water ionization and the positive‐bias‐stress‐induced instability is mainly attributed to the generation of interstitial/substitutional hydrogens and aggregation of hydrogen ions at the backchannel. The temperature and the RH on the device surface jointly determine the moisture diffusion direction. Furthermore, the model is verified by an LT vacuum annealing. The results and the model will be beneficial for the further reliable design of ITZO TFTs in commercial applications.

P‐7: Enhanced Visible Light Response of Amorphous InZnO Thin‐Film Transistors by Hydrogen Doping via Al2O3/SiO2 Gate Dielectric

“…H in the Al2O3 dielectric layer may release into the active layer during the sputtering process and the annealing process, causing hydrogen doping in the active layer film [11]. In the process of hydrogen doping, the below reaction [12] (4) may occur. The H atoms are trapped in the oxygen vacancies to form shallow energy level donors [13], and the formation of more −OH groups in the active layer also leads to the passivation of the oxygen vacancies in the active layer by hydrogen.…”

“…4 is the O 1s XPS spectra of the IZO thin films. Generally, the O 1s spectra can be de-P-7 / J. Huang -convoluted into three subpeaks with binding energy centered at 530.0 ± 0.5 eV (peak 1), 531 ± 0.5 eV (peak 2), and 532 ± 0.5 eV (peak 3), which respectively stands for metal−oxygen (M−O) bonds, metal-oxygen (M−Vo) vacancies, metal−hydroxyl (M−OH) bonds [12]. As shown in Fig.…”

“…By depositing hydrogen-rich Al2O3 dielectric on the top of SiO2, the bandgap of IZO channel is lowered by introducing subgap states, resulting in improved photodetection performance of the device. For the blue light illumination, the photocurrent, photoresponsivity (R), detectivity (D * ), and external quantum efficiency (EQE) are respectively improved from 4.94×10 −7 A to 1.97×10 −6 A, 4.93 A/W to 19.71 A/W, 2.70×10 12 Jone to 5.77×10 12 Jone, and 13.60 to 54.32 after hydrogen doping. By applying a gate pulse voltage, the PPC effect is eliminated.…”

P‐1.9: Optimization of InSnZnO Thin‐Film Transistors Based on Ultra‐Low‐Temperature Annealing Process

“…Amorphous InSnZnO (a-ITZO) has great potential to achieve higher mobility by replacing Ga with Sn [7]. As a representative material in the metal oxide semiconductor, ITZO TFTs have drawn significant interest from both academia and industry due to their higher mobility, resulting from In 5s and Sn 5s orbitals in conduction band minimum [8].…”

P‐1.2: Realization of Visible Detection of InGaZnO Thin‐Film Transistors by Coating (PEA)2PbI4 Light Absorbing Layer

“…Low-cost and low-power photodetectors are essential for environmental detection and medical imaging. InGaZnO (IGZO) thin-film transistor (TFT) is not only widely used in active matrix (AM) displays [1], [2], but also attractive for high-speed and low-noise photodetectors [3] due to its large mobility and low-off current [4]. However, the wide bandgap limits the application of IGZO TFTs in visible light detection [5].…”