Ultrathin ZrOx-Organic Hybrid Dielectric (EOT 3.2 nm) via Initiated Chemical Vapor Deposition for High-Performance Flexible Electronics.

A one-step synthesis method is introduced and used to form an ultrathin, homogeneous organic-inorganic hybrid dielectric film with a high dielectric constant (high-k), based on initiated chemical vapor deposition. The hybrid dielectric is synthesized from tetrakis-dimethyl-amino-zirconium and 2-hydroxyethyl methacrylate, which are a high-k inorganic material and a soft organic material, respectively. A detailed material analysis on the synthesized ZrOx-organic hybrid (Zr-hybrid) is performed. The Zr-hybrid dielectric has a high dielectric constant of nine, leading to a film equivalent oxide thickness (EOT) as low as 3.2 nm, which is the lowest EOT obtained from a flexible dielectric layer to date. The leakage current density (J) is no larger than 6 × 10-7 A/cm2 at 2 MV/cm, and the breakdown field (Ebreak) was ∼3.3 MV/cm. The J of the Zr-hybrid dielectric remains almost constant even under the 2.5% strain condition, while that of the ZrO2 dielectric breaks down electrically at a tensile strain of less than 1.0%. The Zr-hybrid dielectric shows an energy band gap in the range of 5.2-5.4 eV and exhibits a sufficient valence band offset of around 3.0 eV with a pentacene organic semiconductor. The gate stack of the Zr-hybrid dielectric/pentacene semiconductor shows decent metal-oxide-semiconductor field-effect transistor performance even under a tensile strain of 1.67%, indicating that the Zr-hybrid is a promising gate dielectric for advanced flexible electronic applications.

Fermi-Level Unpinning Technique with Excellent Thermal Stability for n-Type Germanium.

A metal-interlayer-semiconductor (M-I-S) structure with excellent thermal stability and electrical performance for a nonalloyed contact scheme is developed, and considerations for designing thermally stable M-I-S structure are demonstrated on the basis of n-type germanium (Ge). A thermal annealing process makes M-I-S structures lose their Fermi-level unpinning and electron Schottky barrier height reduction effect in two mechanisms: (1) oxygen (O) diffusion from the interlayer to the contact metal due to high reactivity of a pure metal contact with O and (2) interdiffusion between the contact metal and semiconductor through grain boundaries of the interlayer. A pure metal contact such as titanium (Ti) provides very poor thermal stability due to its high reactivity with O. A structure with a tantalum nitride (TaN) metal contact and a titanium dioxide (TiO2) interlayer exhibits moderate thermal stability up to 400 °C because TaN has much lower reactivity with O than with Ti. However, the TiO2 interlayer cannot prevent the interdiffusion process because it is easily crystallized during thermal annealing and its grain boundaries act as diffusion path. A zinc oxide (ZnO) interlayer doped with group-III elements, such as an aluminum-doped ZnO (AZO) interlayer, acts as a good diffusion barrier due to its high crystallization temperature. A TaN/AZO/n-Ge structure provides excellent thermal stability above 500 °C as it can prevent both O diffusion and interdiffusion processes; hence, it exhibits Ohmic contact properties for all thermal annealing temperatures. This work shows that, to fabricate a thermally stable and low resistive M-I-S contact structure, the metal contact should have low reactivity with O and a low work-function, and the interlayer should have a high crystallization temperature and a low conduction band offset to Ge. Furthermore, new insights are provided for designing thermally stable M-I-S contact schemes for any semiconductor material that suffers from the Fermi-level pinning problem.

Congenital Jejunal Diverticular Bleeding in a Young Adult.

Diverticular bleeding of the small bowel is rare and occurs primarily in adults aged more than 60 years. In younger adults, Meckel's diverticulum, a true diverticulum that congenitally occurs in the distal ileum, is the most common cause of diverticular bleeding of the small bowel. Unlike Meckel's diverticula, other kinds of small bowel diverticula are not congenital and their incidence is related to age. Furthermore, congenital true diverticular bleeding of the jejunum in adults is very rare. We report the case of a 24-year-old man with subepithelial tumor-like lesion accompanied with obscure overt gastrointestinal bleeding. This lesion was initially suspected to be a subepithelial tumor based on radiologic tests and capsule endoscopy. He was finally diagnosed with a congenital true diverticulum in the jejunum with the appearance of a Meckel's diverticulum after surgical resection.

Oxyntic gland adenoma endoscopically mimicking a gastric neuroendocrine tumor: A case report.

Gastric adenocarcinoma is one of the most common malignancies worldwide. Histochemical and immunohistologic analyses classify the phenotypes of gastric adenocarcinoma into several groups based on the variable clinical and pathologic features. A new and rare variant of gastric adenocarcinoma with chief cell differentiation (GA-CCD) has recently been recognized. Studies reporting the distinct clinicopathologic characteristics proposed the term oxyntic gland polyp/adenoma because of the benign nature of the GA-CCD. Typically, GA-CCD is a solitary mucosal lesion that develops either in the gastric cardia or fundus. Histologically, this lesion is characterized by tightly clustered glands and anastomosing cords of chief cells. Immunohistochemically, GA-CCD is diffusely positive for mucin (MUC) 6 and negative for MUC2 and MUC5AC. However, other gastric tumors such as a gastric neuroendocrine tumor or fundic gland polyp have been difficult to exclude. Because GA-CCD tends to be endoscopically misdiagnosed as a neuroendocrine tumor or fundic gland polyp, comprehensive assessment and observation by an endoscopist are strongly recommended. Herein, we report a rare case of oxyntic gland adenoma endoscopically mimicking a gastric neuroendocrine tumor that was successfully removed by endoscopic mucosal resection.