Matthew S. Rogers

ZnO nanowire network transistor fabrication on a polymer substrate by low-temperature, all-inorganic nanoparticle solution process

All-solution processed, low-temperature zinc oxide nanowire network transistor fabrication on a polymer substrate was demonstrated. This simple process can produce high resolution metal electrode transistors with inorganic semiconductor nanowire active material in a fully maskless sequence, eliminating the need for lithographic and vacuum processes. The temperature throughout the processing was under 140°C, which will enable further applications to electronics on low-cost, large-area flexible polymer substrates.

A three-dimensional anthropometric solid model of the hand based on landmark measurements

Hand anthropometry data are largely based on measurements of the hand in an outstretched hand posture and are, therefore, difficult to apply to tool gripping hand postures. The purpose of this project was to develop a representative, scalable hand model to be used with 3-D software drawing packages to aid in the ergonomic design of hand tools. Landmarks (66) on the palmar surface of the right hand of 100 subjects were digitised in four functional hand postures and, from these, 3-D surface models of a mean, 25th and 75th% hand were developed. The root mean square differences in hand length between the hand model and the digitised data for the 25th, 50th and 75th percentile hand were 11.4, 3.2 and 8.9 mm, respectively. The corresponding values for hand breadth were 2.0, 0.4 and 1.4 mm. There was good agreement between distances on the digitised hand and the hand model. The application of this research includes improved ergonomic hand tool design through the use of hand anthropometry reference values developed from the general population using grasping hand postures.

Absence of Amorphous Phase in High Power Femtosecond Laser-Ablated Silicon

As femtosecond lasers emerge as viable tools for advanced microscale materials processing, it becomes increasingly important to understand the characteristics of materials resulting from femtosecond laser microablation or micromachining. We conducted transmission electron microscopy experiments to investigate crater structures in silicon produced by repetitive high power femtosecond laser ablation. Comparable experiments of nanosecond laser ablation of silicon were also performed. We found that an amorphous silicon layer that is typically produced in nanosecond laser ablation is absent when the material is irradiated by high power femtosecond laser pulses. Instead, only a defective single crystalline layer was observed in the high power femtosecond laser-ablated silicon crater. Possible mechanisms underlying the formation of the defective single crystalline phase are discussed.

Scalability enhancement of FG NAND by FG shape modification

Floating Gate (FG) NAND scaling has been severely challenged by the reduction of gate coupling ratio (CR) and increase in FG interference (FGI) below 30nm node. Firstly, scalability of inverted ‘T’ shaped FG is evaluated by 3D electrostatics simulation. It is shown that coupling ratio (CR) and Floating Gate Interference (FGI) performance can be maintained at the level of 34nm technology down to 13nm node by engineering key aspects of the FG shape namely FG top width (FGW) and effective field height (EFH) in addition to conventional scaling approaches of IPD thinning and spacer к reduction. Secondly, FG shaping is demonstrated down to FGW of 3nm and EFH of 5nm using a sacrificial oxidation technology with no birds beak to demonstrate fabrication feasibility.

In situ crystal growth imaging during explosive crystallization

Explosive crystallization of amorphous germanium of 0.89 and 1.80 microns in thickness deposited on quartz substrates was investigated. A scalloped, mixed, and columnar regime was observed. In situ images captured using dark field imaging reveal the shape of the explosive crystallization front. Crystallization was induced by a frequency tripled Nd:YAG laser (λ = 355 nm) focused to a tight line. A second Nd:YAG laser was frequency doubled (λ = 532 nm) and used as an illumination source for two time resolved pictures. The shape and speed of the explosive crystallization front is observed for various heat loss parameters and crystallization regimes and is generally in good agreement with the literature. Surface morphology is inspected by Atomic Force Microscopy (AFM) after explosive crystallization has completed.