Hydrogen-Doping-Enabled Boosting of the Carrier Mobility and Stability in Amorphous IGZTO Transistors

Abstract

This study investigated the effect of hydrogen (H) on the performance of amorphous In–Ga–Zn–Sn oxide (a-In0.29Ga0.35Zn0.11Sn0.25O) thin-film transistors (TFTs). Ample H in plasma-enhanced atomic layer deposition (PEALD)-derived SiO2 can diffuse into the underlying a-IGZTO film during the postdeposition annealing (PDA) process, which affects the electrical properties of the resulting TFTs due to its donor behavior in the a-IGZTO. The a-In0.29Ga0.35Zn0.11Sn0.25O TFTs at the PDA temperature of 400 °C exhibited a remarkably higher field-effect mobility (μFE) of 85.9 cm2/Vs, a subthreshold gate swing (SS) of 0.33 V/decade, a threshold voltage (V TH) of −0.49 V, and an I ON/OFF ratio of ∼108; these values are superior compared to those of unpassivated a-In0.29Ga0.35Zn0.11Sn0.25O TFTs (μFE = 23.3 cm2/Vs, SS = 0.36 V/decade, and V TH = −3.33 V). In addition, the passivated a-In0.29Ga0.35Zn0.11Sn0.25O TFTs had good stability against the external gate bias duration. This performance change can be attributed to the substitutional H doping into oxygen sites (HO) leading to a boost in n e and μFE. In contrast, the beneficial HO effect was barely observed for amorphous indium gallium zinc oxide (a-IGZO) TFTs, suggesting that the hydrogen-doping-enabled boosting of a-IGZTO TFTs is strongly related to the existence of Sn cations. Electronic calculations of VO and HO using density functional theory (DFT) were performed to explain this disparity. The introduction of SnO2 in a-IGZO is predicted to cause a conversion from shallow VO to deep VO due to the lower formation energy of deep VO, which is effectively created around Sn cations. The formation of HO by H doping in the IGZTO facilitates the efficient connection of atomic states forming the conduction band more smoothly. This reduces the effective mass and enhances the carrier mobility.

Unlocking Neuromorphic Vision: Advancements in IGZO-Based Optoelectronic Memristors with Visible Range Sensitivity

“…Both of these processes increase subgap states, leading to improved optical absorption. , By passivation of the defect states, hydrogen doping can also improve the mobility of the charge carriers. This allows for faster and more efficient transport of photogenerated carriers, leading to a higher photocurrent and quicker response times. , This is confirmed by the significantly increased photocurrents of the doped memristor, presented in Figure d–f. In fact, for 10 s illumination, the I light / I dark ratio increases from 1.3 to 12, from 14 to 93, and from 46 to 179 for wavelengths of 505, 405, and 365 nm, respectively.…”

Strong Immunity to Drain-Induced Barrier Lowering in ALD-Grown Preferentially Oriented Indium Gallium Oxide Transistors

“…To date, numerous studies have been reported to increase the μ FE in oxide TFTs using various approaches such as Sn-doped InGaZnO (IGZO), − optimization of the cation composition, − crystallization, − heterojunctions, − dual-gate structures, adjusting channel thickness, and postdeposition annealing (PDA) temperature. , Among them, the crystallization via the PDA is one of the simplest and the most effective approaches to improve the μ FE . However, the crystallization of oxide semiconductors with a ZnO component is generally accomplished at a high temperature (>700 °C) due to its corner-sharing crystal configuration different from In 2 O 3 and Ga 2 O 3 with an edge-sharing configuration crystal structure .…”

Double-gate structure enabling remote Coulomb scattering-free transport in atomic-layer-deposited IGO thin-film transistors with HfO2 gate dielectric through insertion of SiO2 interlayer

“…In this context, several approaches have been proposed to ensure high mobility AOS TFTs, such as heterojunction structures using quasi-two-dimensional electron gas (q2DEG) 5 , 11 , crystallization 10 , 12 , hydrogen doping 7 , and multi-gate architecture 14 – 19 . Amongst, adopting the multi-gate architecture, such as double-gate (DG), tri-gate and gate-all-around (GAA), is considered promising due to the outstanding current boosting ability.…”