Specific contact resistivity reduction in amorphous IGZO thin-film transistors through a TiN/IGTO heterogeneous interlayer.

Oxide semiconductors have gained significant attention in electronic device industry due to their high potential for emerging thin-film transistor (TFT) applications. However, electrical contact properties such as specific contact resistivity (ρC) and width-normalized contact resistance (RCW) are significantly inferior in oxide TFTs compared to conventional silicon metal oxide semiconductor field-effect transistors. In this study, a multi-stack interlayer (IL) consisting of titanium nitride (TiN) and indium-gallium-tin-oxide (IGTO) is inserted between source/drain electrodes and amorphous indium-gallium-zinc-oxide (IGZO). The TiN is introduced to increase conductivity of the underlying layer, while IGTO acts as an n+-layer. Our findings reveal IGTO thickness (tIGTO)-dependent electrical contact properties of IGZO TFT, where ρC and RCW decrease as tIGTO increases to 8 nm. However, at tIGTO > 8 nm, they increase mainly due to IGTO crystallization-induced contact interface aggravation. Consequently, the IGZO TFTs with a TiN/IGTO (3/8 nm) IL reveal the lowest ρC and RCW of 9.0 × 10-6 Ω·cm2 and 0.7 Ω·cm, significantly lower than 8.0 × 10-4 Ω·cm2 and 6.9 Ω·cm in the TFTs without the IL, respectively. This improved electrical contact properties increases field-effect mobility from 39.9 to 45.0 cm2/Vs. This study demonstrates the effectiveness of this multi-stack IL approach in oxide TFTs.

Oxide and 2D TMD semiconductors for 3D DRAM cell transistors.

As the downscaling of conventional dynamic random-access memory (DRAM) has reached its limits, 3D DRAM has been proposed as a next-generation DRAM cell architecture. However, incorporating silicon into 3D DRAM technology faces various challenges in securing cost-effective high cell transistor performance. Therefore, many researchers are exploring the application of next-generation semiconductor materials, such as transition oxide semiconductors (OSs) and metal dichalcogenides (TMDs), to address these challenges and to realize 3D DRAM. This study provides an overview of the proposed structures for 3D DRAM, compares the characteristics of OSs and TMDs, and discusses the feasibility of employing the OSs and TMDs as the channel material for 3D DRAM. Furthermore, we review recent progress in 3D DRAM using the OSs, discussing their potential to overcome challenges in silicon-based approaches.

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

Amorphous IGZO (a-IGZO) thin-film transistors (TFTs) are standard backplane electronics to power active-matrix organic light-emitting diode (AMOLED) televisions due to their high carrier mobility and negligible low leakage characteristics. Despite their advantages, limitations in color depth arise from a steep subthreshold swing (SS) (≤ 0.1 V/decade), necessitating costly external compensation for IGZO transistors. For mid-size mobile applications such as OLED tablets and notebooks, it is important to ensure controllable SS value (≥ 0.3 V/decade). In this study, a conversion mechanism during plasma-enhanced atomic layer deposition (PEALD) is proposed as a feasible route to control the SS. When a pulse of a diethylzinc (DEZn) precursor is exposed to the M2 O3 (M = In or Ga) surface layer, partial conversion of the underlying M2 O3 to ZnO is predicted on the basis of density function theory calculations. Notably, significant distinctions between In-Ga-Zn (Case I) and In-Zn-Ga (Case II) films are observed: Case II exhibits a lower growth rate and larger Ga/In ratio. Case II TFTs with a-IGZO (subcycle ratio of In:Ga:Zn = 3:1:1) show reasonable SS values (313 mV decade-1 ) and high mobility (µFE ) of 29.3 cm2 Vs-1 (Case I: 84 mV decade-1 and 33.4 cm2 Vs-1 ). The rationale for Case II's reasonable SS values is discussed, attributing it to the plausible formation of In-Zn defects, supported by technology computer-aided design (TCAD) simulations.

Comparative Study on Indium Precursors for Plasma-Enhanced Atomic Layer Deposition of In2O3 and Application to High-Performance Field-Effect Transistors.

Indium oxide (In2O3) is a transparent wide-bandgap semiconductor suitable for use in the back-end-of-line-compatible channel layers of heterogeneous monolithic three-dimensional (M3D) devices. The structural, chemical, and electrical properties of In2O3 films deposited by plasma-enhanced atomic layer deposition (PEALD) were examined using two different liquid-based precursors: (3-(dimethylamino)propyl)-dimethyl indium (DADI) and (N,N-dimethylbutylamine)trimethylindium (DATI). DATI-derived In2O3 films had higher growth per cycle (GPC), superior crystallinity, and low defect density compared with DADI-derived In2O3 films. Density functional theory calculations revealed that the structure of DATI can exhibit less steric hindrance compared with that of DADI, explaining the superior physical and electrical properties of the DATI-derived In2O3 film. DATI-derived In2O3 field-effect transistors (FETs) exhibited unprecedented performance, showcasing a high field-effect mobility of 115.8 cm2/(V s), a threshold voltage of -0.12 V, and a low subthreshold gate swing value of <70 mV/decade. These results were achieved by employing a 10-nm-thick HfO2 gate dielectric layer with an effective oxide thickness of 3.9 nm. Both DADI and DATI-derived In2O3 FET devices exhibited remarkable stability under bias stress conditions due to a high-quality In2O3 channel layer, good gate dielectric/channel interface matching, and a suitable passivation layer. These findings underscore the potential of ALD In2O3 films as promising materials for upper-layer channels in the next generation of M3D devices.

High-Performance Thin-Film Transistor with Atomic Layer Deposition (ALD)-Derived Indium-Gallium Oxide Channel for Back-End-of-Line Compatible Transistor Applications: Cation Combinatorial Approach.

In this paper, the feasibility of an indium-gallium oxide (In2(1-x)Ga2xOy) film through combinatorial atomic layer deposition (ALD) as an alternative channel material for back-end-of-line (BEOL) compatible transistor applications is studied. The microstructure of random polycrystalline In2Oy with a bixbyite structure was converted to the amorphous phase of In2(1-x)Ga2xOy film under thermal annealing at 400 °C when the fraction of Ga is ≥29 at. %. In contrast, the enhancement in the orientation of the (222) face and subsequent grain size was observed for the In1.60Ga0.40Oy film with the intermediate Ga fraction of 20 at. %. The suitability as a channel layer was tested on the 10-nm-thick HfO2 gate oxide where the natural length was designed to meet the requirement of short channel devices with a smaller gate length (<100 nm). The In1.60Ga0.40Oy thin-film transistors (TFTs) exhibited the high field-effect mobility (µFE) of 71.27 ± 0.98 cm2/(V s), low subthreshold gate swing (SS) of 74.4 mV/decade, threshold voltage (VTH) of -0.3 V, and ION/OFF ratio of >108, which would be applicable to the logic devices such as peripheral circuit of heterogeneous DRAM. The in-depth origin for this promising performance was discussed in detail, based on physical, optical, and chemical analysis.

Multi-Center, Randomized, Double-Blind, Placebo-Controlled, Exploratory Study to Evaluate the Efficacy and Safety of HAD-B1 for Dose-Finding in EGFR Mutation Positive and Locally Advanced or Metastatic NSCLC Subjects Who Need Afatinib Therapy.

Afatinib is a target anticancer drug of the second-generation EGFR TKI type, showing an advantage in treatment effect compared to conventional chemotherapy. However, patients on EGFR-TKI drugs also usually progress after 9 to 13 months according to secondary resistance. HAD-B1 is composed of drugs that are effective against lung cancer. This study is an exploratory study to evaluate the efficacy and safety between dosage groups by conducting a clinical trial in subjects requiring afatinib drug treatment in non-small cell lung cancer with EGFR mutation positive to determine the optimal dosage for HAD-B1 administration. At the final visit compared to before administration, each change in the disease control rate was measured according to the HAD-B1 doses of the test group 1 (972 mg), the test group 2 (1944 mg), and the control group. The efficacy and safety of HAD-B1 were compared and evaluated through sub-evaluation variables. As a result of the study, there was no statistically significant difference in the disease control rate at 12 weeks after dosing, but complete and partial remission were evaluated as 1 patient each in the test group 1, and none in the other groups. There was no statistically significant difference between groups in the sub-evaluation variable. In addition, there was no problem of safety from taking the test drug. However, the initially planned number of subjects was 66, but the number of enrolled subjects was only 14, which may limit the results of this study.

Acute cocaine induces endothelin-1-dependent constriction of rabbit basilar artery.

It has been postulated that ischemic stroke due to acute cocaine usage involves constriction of the cerebral vasculature. However, the mechanism underlying the constriction remains unclear. This study tested whether cocaine constriction was mediated via endothelin-1. Cocaine suffusion induced maintained constriction in the rabbit basilar artery in situ. The constriction was relaxed by PD145065, an endothelin A and B receptor antagonist. These results support the hypothesis that constriction of the cerebral vasculature due to acute cocaine exposure is via endothelin-1 release. Endothelin receptor antagonists may be of therapeutic benefit in cerebrovascular pathophysiologies involving cocaine constriction.