Tailored Self-Assembled Monolayer using Chemical Coupling for Indium-Gallium-Zinc Oxide Thin-Film Transistors: Multifunctional Copper Diffusion Barrier

Controlling the contact properties of a copper (Cu) electrode is an important process for improving the performance of an amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistor (TFT) for high-speed applications, owing to the low resistance-capacitance product constant of Cu. One of the many challenges in Cu application to a-IGZO is inhibiting high diffusivity, which causes degradation in the performance of a-IGZO TFT by forming electron trap states. A self-assembled monolayer (SAM) can perfectly act as a Cu diffusion barrier (DB) and passivation layer that prevents moisture and oxygen, which can deteriorate the TFT on-off performance. However, traditional SAM materials have high contact resistance and low mechanical-adhesion properties. In this study, we demonstrate that tailoring the SAM using the chemical coupling method can enhance the electrical and mechanical properties of a-IGZO TFTs. The doping effects from the dipole moment of the tailored SAMs enhance the electrical properties of a-IGZO TFTs, resulting in a field-effect mobility of 13.87 cm²/V·s, an on-off ratio above 10⁷, and a low contact resistance of 612 Ω. Because of the high electrical performance of tailored SAMs, they function as a Cu DB and a passivation layer. Moreover, a selectively tailored functional group can improve the adhesion properties between Cu and a-IGZO. These multifunctionally tailored SAMs can be a promising candidate for a very thin Cu DB in future electronic technology.

A Review of Phototransistors Using Metal Oxide Semiconductors: Research Progress and Future Directions

Metal oxide thin-film transistors have been continuously researched and mass-produced in the display industry. However, their phototransistors are still in their infancy. In particular, utilizing metal oxide semiconductors as phototransistors is difficult because of the limited light absorption wavelength range and persistent photocurrent (PPC) phenomenon. Numerous studies have attempted to improve the detectable light wavelength range and the PPC phenomenon. Here, recent studies on metal oxide phototransistors are reviewed, which have improved the range of light wavelengths and the PPC phenomenon by introducing an absorption layer of oxide or non-oxide hybrid structure. The materials of the absorption layer applied to absorb long-wavelength light are classified into oxides, chalcogenides, organic materials, perovskites, and nanodots. Finally, next-generation convergence studies combined with other research fields are introduced and future research directions are detailed.

Preoperative assessment of gastric carcinoma: value of two-phase dynamic CT with mechanical iv. injection of contrast material

OBJECTIVE

The purpose of this study was to evaluate the utility of two-phase dynamic CT performed with mechanical IV injection of a bolus of contrast medium after oral intake of water in the preoperative staging of gastric cancers.

SUBJECTS AND METHODS

We performed incremental dynamic CT in 52 patients with pathologically proved gastric cancers. Dynamic CT findings were prospectively analyzed and correlated with surgical and histopathologic findings. A total of 150 ml of nonionic contrast medium was administered IV with a power injector at a flow rate of 5 ml/sec for 30 sec, and two-phase images were obtained at 30 sec (early phase) and 2 min (equilibrium phase) after the start of bolus injection.

RESULTS

Forty-one advanced gastric carcinomas showed a moderate to marked degree of heterogeneous enhancement in the early phase and homogeneous enhancement of the entire lesion in the equilibrium phase of dynamic CT. The primary tumors were correctly detected with dynamic CT in five (56%) of the nine early gastric cancers and in 41 (95%) of the 43 advanced gastric cancers. The overall detection rate of gastric cancers was 88% (46 of 52 cases). The accuracies of dynamic CT according to TNM staging in determining the depth of tumor invasion, the degree of serosal invasion, and regional lymph node metastasis were 65% (34 of 52 cases), 83% (38 of 46 cases), and 70% (32 of 46 cases), respectively.

CONCLUSION

Our findings show that two-phase incremental dynamic CT with mechanical IV injection of a bolus of contrast medium after oral intake of water improves the diagnostic accuracy of CT over that provided by conventional CT in the preoperative staging of gastric cancers.