Life Sciences Commons^™

Investigation Of Dislocations In Gaas Using Cathodoluminescence In The Scanning Electron Microscope, K. L. Pey, J. C. H. Phang, D. S. H. Chan

Scanning Microscopy

Electrically active dislocations in Si-doped {100} GaAs substrates were observed using the cathodoluminescence (CL) technique in the scanning electron microscope (SEM). CL contrast profiles were experimentally obtained from the dislocations at different beam energies. Based on the CL model for localized defects in semiconductors developed earlier by Pey, the depths of the dislocations were found by locating the beam energy at which maximum CL contrast occurred. A preferential etching technique for {100} GaAs was employed to reveal the dislocations and to measure their depths. The etched depths obtained were compared to the predicted results from the theoretical model developed. The …

Scanning Electron Microscopic Studies Of The Palatine Mucosa And Its Microvascular Architecture In The Rat, S. Sugioka, H. Ike

Scanning Microscopy

Detailed observations were made on the structure and microvasculature of the palatine mucosa of the rat by means of microvascular corrosion casts and epithelium-digested specimens using scanning electron microscopy. The rat palate was divided into four regions according to the characteristics of the palatine plicae. In the atrial region, no transverse palatine plicae were present, but there were longitudinal ridges and folds in the median area. These structures contribute to the transportation of rough and grainy foods with the assistance of the hairy buccal part. Capillary loops in the ridge and folds appeared as continuous, sagittally elongated loops. In the …

A Simulation Model For Electron Irradiation Induced Specimen Charging In A Scanning Electron Microscope, D. S. H. Chan, K. S. Sim, J. C. H. Phang

Scanning Microscopy

A numerical model has been formulated to simulate the dynamics of specimen charging in a scanning electron microscope. In this model, the electric field due to imposed boundary conditions and fixed charges is solved by the finite element method. The empirical electron yield data are stored in "Universal Yield Curves (UYC)". These UYCs control the generation of secondary and backscattered electrons from various materials. The electrons emitted from electron-solid interactions are tracked using a leapfrog integration scheme. Excess charges generated on the surface of electrically floating solids are assigned to numerical grids using a linear charge redistribution scheme. The validity …

An Energy Dependent Model For Type I Magnetic Contrast In The Scanning Electron Microscope, W. K. Chim, D. S. H. Chan, J. C. H. Phang, T. S. Low, S. Thirumalai

Scanning Microscopy

The modelling of the magnetic contrast phenomenon in the scanning electron microscope (SEM) is important in understanding the physics of the contrast mechanism and the associated signal detection. In this paper, we report an improved analytical model for Type I magnetic contrast calculations using an approximate form of the Chung and Everhart secondary electron (SE) energy distribution. Previous studies have neglected this factor by assuming a mono-energetic model in order to simplify the calculations. This new model can be used to study different material specimens by appropriate choice of the work function and field-distance integral. The effect of energy filtering …

Scanning Electron Microscopy Of Age-Related Changes In The C57bl/6j Mouse Cochlea, Kunihiro Mizuta, Osamu Nozawa, Hirofumi Morita, Tomoyuki Hoshino

Scanning Microscopy

Hair cells and nerve fibers inside the organ of Corti of the C57BL/6J mouse, which is known as the precocious presbycusis model, were studied using the scanning electron microscope. For this study, we used thick serial sections cut from celloidin blocks.

In the 5-week-old mice, hair cell loss was not seen. The upper tunnel radial fibers crossed the upper part of the tunnel of Corti and entered the Nuel's space between the outer pillar cells. The fibers varied in diameter and showed many varicosities. The basilar fibers emerged into the tunnel of Corti beneath the upper tunnel radial fibers …

Calculation Of A Topographic Contrast In The Scanning Electron Microscope, M. Kotera, T. Fujiwara, S. Yamaguchi, H. Suga

Scanning Microscopy

A direct simulation of electron scattering in solids is developed. Using this simulation, a topographic contrast found in the scanning electron microscope is quantitatively discussed. The surface topography studied here is a rectangular rod pattern and a rectangular groove pattern at an infinite horizontal plane surface of Al. We quantify characteristics of the secondary electron image and of the backscattered electron image at the topography. The intensity profile at the bottom surface of the groove pattern is roughly approximated by an analytical model.

Efficiency Of The Secondary Electron Detector In The Scanning Electron Microscope, Zbigniew Czyzewski, David C. Joy

Scanning Microscopy

The efficiency of the secondary electron detector in the scanning electron microscope (SEM) is one of the most important factors affecting the imaging process of the SEM. To compute the detector efficiency, the electrostatic field inside a specimen chamber must be known. A simple way of performing such calculations is to use a spreadsheet program which has a built-in capability of storing and performing some operations on three-dimensional matrices. Using a spreadsheet program makes it possible to solve the Laplace equation and calculate electron trajectories in geometrically complex electrostatic fields. This technique is applied to the estimation of detector efficiency …