Deep Trench Isolation and Inverted Pyramid Array Structures Used to Enhance Optical Efficiency of Photodiode in CMOS Image Sensor via Simulations.

The photodiode in the backside-illuminated CMOS sensor is modeled to analyze the optical performances in a range of wavelengths (300-1100 nm). The effects of changing in the deep trench isolation depth (DTI) and pitch size (d) of the inverted pyramid array (IPA) on the peak value () of optical efficiency (OE) and its wavelength region are identified first. Then, the growth ratio (GR) is defined for the change in these wavelength ranges to highlight the effectiveness of various DTI and d combinations on the and evaluate the difference between the pixel arrays with and without the DTI + IPA structures.

Effects of prestrain applied to poly(ethylene terephthalate) substrate on microstructures and morphologies of porous TiO(2) film and optical scattering behaviors of light.

A mold was designed to simulate a thin ceramic film coating on a soft, flexible substrate using a rotating deposition system. With this mold, three prestrains (2%, 4%, and 6%) were applied to a polyethylene terephthalate (PET) substrate before the deposition of a thin TiO(2) film. The contact angle of the substrate and, thus, the mean TiO(2) particle size were affected by the prestrain.

Characterization of the elastic and viscoelastic properties of dentin by a nanoindentation creep test.

Dentin is the main supporting structure of teeth, but its mechanical properties may be adversely affected by pathological demineralization. The purposes of this study were to develop a quantitative approach to characterize the viscoelastic properties of dentin after de- and re-mineralization, and to examine the elastic properties using a nanoindentation creep test. Dentin specimens were prepared to receive both micro- and nano-indentation tests at wet and dry states.

Microstructural, electrical, and mechanical properties of graphene films on flexible substrate determined by cyclic bending test.

Three kinds of graphene/polyimide specimen were prepared via transfer with 3, 6, and 9 graphene layers, respectively. A self-designed bending tester was applied to carry out cyclic bending tests with various bending cycles and bending frequencies. The variations of electrical resistance of the specimens during the bending process and the rate of increase of electrical resistance with the number of bending cycles and bending frequency for various total graphene thicknesses were determined.

Nanotribology of self-assembled monolayer with a probe tip investigated using molecular dynamics simulations.

The nanotribology of an alkanethiol self-assembled monolayer (SAM) under tilt contact with a scanning probe tip is studied using molecular dynamics (MD) simulations. The tilt contact is described in terms of the tilt angle and the magnitude of the specimen-tip separation. The effects of tilt angle and magnitude of the specimen-tip separation on the normal force, friction force, friction coefficient, shear strength of the tip-SAM junction, and self-recovery characteristics are evaluated during the scanning probe tip process at a temperature of 300 K.

Stress-strain analysis for evaluating the effect of the orientation of dentin tubules on their mechanical properties and deformation behavior.

A model whose porosity does not vary with compression depth is developed for evaluating the mechanical properties of dentin tubules with various orientation angles from micro-pillar nanocompression tests. Experimental results for a range of loading rates indicate that the yielding parameters and the elastic modulus are little affected by the creep behavior. For a given compression depth, the hardness, elastic modulus, and yielding strength decrease with increasing orientation angle of dentin.

Effect of chain length of self-assembled monolayers in dip-pen nanolithography using molecular dynamics simulations.

The pattern transfer mechanism of an alkanethiol self-assembled monolayer (SAM) with different chain lengths during the dip-pen nanolithography (DPN) process and pattern characterizations are studied using molecular dynamics (MD) simulations. The mechanisms of molecular transference, alkanethiol meniscus characteristics, surface adsorbed energy, transfer number, and pattern formation are evaluated during the DPN process at room temperature. The simulation results clearly show that the molecular transfer ability in DPN is strongly dependent on the chain length.

Formation mechanism and mechanics of dip-pen nanolithography using molecular dynamics.

Molecular dynamics simulations are used to investigate the mechanisms of molecular transference, pattern formation, and mechanical behavior in the dip-pen nanolithography (DPN) process. The effects of deposition temperature were studied using molecular trajectories, the meniscus characteristic, surface absorbed energy, and pattern formation analysis. At the first transferred stage (at the initial indentation depth), the conformation of SAM molecules lies almost on the substrate surface.

Multiscale particle dynamics on nanocontact and sliding friction.

A multiscale particle method for coupling continuum and molecular models is described. In this method, the continuum model was assumed to be in a lattice form and can be applied in noncharacteristic areas or far away regions from the large deformations to save computational time. Defining a series of critical energies for different lattice sizes is convenient for lattice refinement.

A new method for determining the strain energy release rate of an interface via force-depth data of nanoindentation tests.

Indentation forces, including constant rate and oscillating mode, were applied to SiO(2)/Si and diamond-like carbon (DLC)/Si specimens. A two-stage behavior was exhibited in the force-depth results after delamination occurred. When the depth was smaller than the threshold value, a linear load-depth relationship was exhibited because the debonded film was suspended over the substrate.

Characteristics of water strider legs in hydrodynamic situations.

This study investigated the forces and the cross-section images of a water strider's leg through experimental observations. In the vertical direction, the spring coefficients were found to be 0.6 N/m for the leg and 0.

Molecular Dynamics Simulations of the Roller Nanoimprint Process: Adhesion and Other Mechanical Characteristics.

Molecular dynamics simulations using tight-binding many body potential are carried out to study the roller imprint process of a gold single crystal. The effect of the roller tooth's taper angle, imprint depth, imprint temperature, and imprint direction on the imprint force, adhesion, stress distribution, and strain are investigated. A two-stage roller imprint process was obtained from an imprint force curve.

Adhesion forces and contact angles of water strider legs.

This study investigated the adhesion (pull-off) force and contact angles of a water strider's leg. During hydrostatic experiments, the adhesion force was found to be 2 dyn. The image of a cross section of a live leg contacted with a deformed water surface provided the contact angle of 168.

Initial and adhesive contact between a diamond indenter and polydimethylsiloxane.

Detailed observations for the initial and adhesive contact of polydimethylsiloxane indentations with sharp indenters are proposed and discussed in this study. In dry experiments, the load-depth results revealed an almost reversible feature, which indicated elastic deformation. Significant initial penetration depths, created during the finding surface process, were found.

Theoretical modeling developed to evaluate the hardness and reduced modulus for the C/a-Si composite film using nanoindentation tests.

A general mechanical model, which is composed of the mechanical models employed to describe the contact behaviors and deformations arising in all layers (including the substrate), is successfully developed in the present study for multilayer specimens in order to evaluate the contact projected area by a theoretical model, and thus the hardness and reduced modulus, using nanoindentation tests. The governing differential equations for the depth solutions of the indenter tip formed at all layers of the specimen under their contact load are developed individually. The influence of the material properties of the substrate on a multilayer specimen's hardness and reduced modulus at various indentation depths can thus be evaluated.