Yamamoto, Hiromichi
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Publication Statistical Process Control of Alignment Module of NX2600(2015-05-12) Yamamoto, HiromichiPublication Statistical Process Control of 80plus Reactive Ion Etcher(2015-05-06) Yamamoto, HiromichiPublication Publication Fabrication of Organic Thin Film Transistors using Inkjet Printing of PEDOT:PSS(2019-11-13) Das, Sourajit; Venkatakrishnan, Akshaya; Yamamoto, Hiromichi; Watson, George PatrickAn Organic Thin Film Transistors (OTFT) using poly(3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) is fabricated using a Fuji film Dimatix Inkjet printer, and successfully shows the characteristics of field effect transistor as a result of optimization of the inkjet printing condition. The V-I characteristics of the two devices also satisfy the fundamental property of transistors that wider is the channel length, smaller is the drain current. Another significant property is observed that the higher gate voltage induces the higher drain current as it allows larger carrier concentration in the channel region.Publication Statistical Process Control of PECVD(2015-05-06) Yamamoto, HiromichiPublication Inkjet Printing of Graphene(2020-12-17) Hoang, Lauren; Yamamoto, Hiromichi; Suh, Yeonjoon; Watson, George PatrickThe optimization of inkjet printing graphene using a Fujifilm Dimatix Inkjet printer, is described in this study. The number of printing passes were varied, and relatively uniform lines were obtained. The printing parameter considerations and optimized printing parameters for graphene are also discussed.Publication Stress in Silicon Oxide Thin Films Grown by Dry Thermal Oxidation(2020-11-13) Muduli, Manisha; Yamamoto, HiromichiDry thermal oxidation is performed at 900, 950, 1000, and 1050 C in fused silica tube furnace (Sandvik)for 10, 20, 50, 100 and 200 min. The properties of the thin-films such as refractive index and stress arestudied in this paper. Refractive indexes of the thin-films are obtained using ellipsometer and decreasesfrom 1.78 to 1.46 as the film thickness increases.Stress of the thin-films is theoretically calculated,experimentally measured and then compared.Stress is calculated theoretically using Stoney’s stressequation and Goklaney’s stress equations. Stress is measured experimentally using the profilometer. Ex-perimentally measured stress and refractive indexes are then compared to discuss the density of the thin-films.Publication Progress Report I: Fabrication of Nanopores in Silicon Nitride Membranes using Self-Assembly of PS-b-PMMA(2019-03-05) Joshi, Unnati; Venkatesh, Vishal; Yamamoto, HiromichiThis progress report describes fabrication of silicon nitride membranes from Si wafers using cleanroom techniques, and of nanopore preparation via a self-assembled PS-b-PMMA film. A 36.9 µm thick membrane is successfully prepared by KOH wet etching. The membrane is a layered structure of 36.8 µm thick Si and 116 nm thick silicon nitride. It is also exhibited that in the 47 nm thick PS-b-PMMA film, the nanopore structure is observed in the vicinity of a dust particle, but most of the area indicates lamellar domain structure. The thickness of PS-b-PMMA film will be optimized to prepare a complete nanopore template in the future work.Publication Thin Dry Silicon Oxide Films Grown by Thermal Oxidation(2020-03-18) Muduli, Manisha; Yamamoto, HiromichiDry thermal oxidation is performed at 900, 950, 1000, and 1050 C in fused silica tube furnace (Sandvik) for 10, 20, 50, 100 and 200 min. The results are analyzed by both of Deal-Grove model and the method of Gerlach, Maser, and Saad. In the analysis using the Deal-Grove model, the parabolic rate constants are obtained to be 2.1, 7.0, 17.5, and 42.4 nm^2/min at 900, 950, 1000, and 1050 C, respectively, and the linear rate constants are acquired to be 0.2, 0.4, 0.8, and 1.2 nm/min at 900, 950, 1000, 1050 C, respectively. Activation energies of the parabolic rate constant and the linear rate constant are obtained to be 2.67 and 1.55 eV, respectively. In the analysis using the method of Gerlach, Maser, and Saad, the activation energy of the oxide growth rate for the 5 nm thick oxide is obtained to be 2.49 eV, whereas that for the 40 nm thick oxide to be 1.93 eV. The film uniformity for 30 nm thickness shows more than 10%, while that for the thickness of more than 50 nm indicates less than 5%, suggesting that measurement on 30 nm thick film using Filmetrics F50 is not still accurate enough. Standard deviation and coefficient of variation are also examined to discuss the film uniformity.Publication Standard Operating Procedures of Tools in Quattrone Nanofabrication Facility(2015-04-18) Yamamoto, Hiromichi