Shuhei Yoshitomi

21.3: 4.0 In. QVGA AMOLED Display Using In‐Ga‐Zn‐Oxide TFTs with a Novel Passivation Layer

We have developed a 4.0 inch QVGA AMOLED display using amorphous In-Ga-Zn-Oxide TFTs, focusing on a passivation layer. Threshold voltage of the TFTs can be controlled to have “normally off” characteristics by using SiOx with a low hydrogen content. Besides, small subthreshold swing and high saturation mobility are obtained.

P-9: Numerical Analysis on Temperature Dependence of Characteristics of Amorphous In-Ga-Zn-Oxide TFT

We fabricated inverted-staggered amorphous In-Ga-Zn-O (a-IGZO) TFTs and measured temperature dependence of the TFT characteristics. A Vth shift between 120°C and 180°C was as large as about 4 V. In the analysis with 2-D numerical simulation, we could reproduce the measured result by assuming two kinds of donor-like states as carrier generation sources.

49.4: High-definition Top-emitting AMOLED Display with Highly Reliable Oxide Semiconductor Field Effect Transistors

We have developed a highly efficient top-emitting white OLED by employing a stable reflective anode structure and a p-doped buffer layer. Furthermore, combining the white OLED with color filters, we succeeded in fabricating a prototype of a high-definition AMOLED display having highly reliable OS-FETs as the backplane.

36.4: 3.4‐inch Full‐Color QHD AMOLED Display using Large‐Size Flexible Substrate with Highly Reliable OS‐FETs

We report a 300mm × 360mm flexible FET substrate made by our transfer technology and 3.4-inch full-color AMOLED display with oxide FET flexible substrate. Our transfer technology has advantages in applicability for a large-size substrate and cost performance because laser irradiation is not needed.

Evaluation of Organic Monolayers Formed on Si(111): Exploring the Possibilities for Application in Electron Beam Nanoscale Patterning

The methods of preparing organic monolayers on Si(111), the effects of electron-beam irradiation onto these monolayers, and the deposition of metal atoms over the irradiated areas have been investigated in order to develop a process of mass-scale production of nanometer-scale patterns on Si(111) wafer surfaces. The organic monolayers were fabricated on hydrogen-terminated Si(111) wafer surfaces using previously reported methods for the electrolysis of para-substituted benzenediazonium salts and the Grignard reaction with various alkyl moieties and reaction procedures. Using these electrolysis methods, partially well-defined two-dimensional monolayers were formed, which were, however, obscured by precipitated by-products. The Grignard reaction deposited homogeneous monolayer moieties of alkyl groups which were randomly arranged and are suitable for surface passivation. Electron-beam bombardment of the organic monolayers on Si(111) was performed in an atmosphere of O2 or H2O. The bombarded area was effectively oxidized in a well-controlled manner. By immersing the bombarded specimen into an aqueous NiSO4+(NH4)2SO4 solution, Ni was selectively impregnated only within the area of electron bombardment. Based on these results, application of organic monolayers for fabricating nanometer-scale monolayer patterns is proposed.

Alkyl monolayers on Si(111) as ultrathin electron-beam patterning media

Abstract A process of electron-beam patterning of the surface of a Si(111) wafer was developed by utilizing alkyl monolayers as ultrathin patterning media. We performed chemical benchmark tests of the electron-beam patterning of alkyl monolayers on Si(111) in ambient oxygen, followed by the deposition of a metal on bombarded areas by immersion into an aqueous solution containing metal ions of the metal to be deposited. We investigated practically important issues related to this process, such as the robustness of organic monolayers against oxidation in aqueous media, the contrast enhancement of the bombarded areas by metal deposition, and the detectability of electron-bombarded areas of the monolayers by scanning tunneling microscopy (STM). The alkyl-covered Si(111) surface was significantly resistant to the oxidation by dissolved O2 in pure water, compared to hydrogen-terminated Si(111). By immersion into a solution containing CuSO4+HF+NH4F, electron-bombarded areas were visualized by the presence of the deposit of Cu. Electron-bombarded areas were also distinguishable from intact areas in terms of height contrast or roughness measured by STM. These results indicate the usefulness of alkyl monolayers for nano-scale patterning on silicon wafers.

Possibilities of electron beam nano-meter-scale fabrication of Si(111) using alkyl monolayers

A novel process of electron-beam nanometer-scale fabrication on Si(111) wafer surfaces has been proposed on the basis of application of organic monolayers as the ultimately thin patterning media. The monolayers on Si(111) wafer surfaces composed of alkyl groups (C/sub n/H/sub 2n+1//sup _/) prepared with the Grignard reagents were subjected to electron-beam patterning, and deposition of metals onto the electron-bombarded patterns by immersion into aqueous solutions containing Ni/sup 2+/ or Cu/sup 2+/ ions. This entire process has been put into practice successfully as a benchmark test. The strength of alkyl-covered Si(111) surface against the processing environment such as in vacuum and aqueous solutions has been demonstrated.