Transmitted Electron Beam Research Articles

HRTEM observation of the Si/SiO2 interface

Interfaces with crystalline Si (c-Si) and dry oxide grown over the c-Si have been observed using high resolution transmission electron microscopy (HRTEM). The lattice image of c-Si near the interface varies depending on the specimen thickness. For a very thin region of the specimen, the interface was observed to be very much roughened, and seemed to be abrupt (the so called interfacial layer was not observed between the c-Si and the amorphous SiO2 (a-SiO2)). On the contrary, the interface seemed to be flat and to consist of some steps of one or two monolayers high for the thick region. Furthermore, a lattice image with Si(220) periodicity has been observed at the interface. A possible structure for the Si/SiO2 interface derived from the observed interface image is that the roughened surface of the c-Si protrusions is directly connected to the SiO2 network with no interface layer between them. The observed flat interface of the thick region is a superposed image of the randomly distributed Si protrusions over the direction of the transmitted electron beam. In order to examine the postulated interface structure, a simulation of the lattice image has been performed. The results of the simulation indicate that the half-space image observed at the interface of the thick region can be attributed to the interface roughness, and the abrupt interface image observed for the thin region can be obtained by the same interface structure. Since a completely flat interface cannot provide such a specimen thickness dependence of the image, the (100)Si/SiO2 interface must be rough, and in our sample, the height of the roughness was about 4 monolayers.

Quantitation in thin Sections Within the Electron Microscope

In TEM image formation, the observed contrast variations within thin sections result from differential electron scattering within microregions of varying mass thickness. It is possible to utilize these electron scattering properties to obtain objective information regarding various specimen parameters (1, 2, 3).A pragmatic, empirical approach is described which enables a microscopist to perform physical measurements of thickness of thin sections and estimates of local mass, volume, density and, possibly, molecular configurations within thin sections directly in the microscope. A Faraday cage monitors the transmitted electron beam and permits measurements of electron beam intensities.

Bound states of swift electrons for a 〈111〉 axis of silicon

Quantum-mechanical treatment of the bound states of swift electrons with the single atomic rows is developed. In Si 〈111〉 crystal for 1.0 and 2.0 MeV electrons the energy levels of the various states have been calculated, which are used for the discussion of the measured angular distributions of transmitted electron beam.

A Cold Transmission Stub for the SEM

A simple cold sink stub for the SEM was previously reported. The present modification permits the observation of cold or ambient samples in scanning transmission using the principle of converting the primary transmitted electron beam to a secondary electron source and which is detected in the normal manner.

Image formation in the electron microscope. II. The application of transfer theory to a consideration of inelastic electron scattering

For pt.I see ibid. Vol.4, p782 (1971). The application of transfer theory to image formation by the inelastic component of the transmitted electron beam is discussed. The analysis includes the effects of chromatic aberration of the final image. In particular, it is shown that the chromatic aberration effect due to the inelastic component may be effectively cancelled by underfocus of the objective lens. In relation to the formation of image by the inelastically scattered electrons the coherence and the localization of the inelastically scattered wave is discussed.

Stereography of Freeze Etched Replicas

The frequent analogy made between the appearance of freeze etch replicas and the lunar landscape is appropriate in the sense that both are best viewed as if they were opaque irregular surfaces illuminated from behind and to the side of the observer. Replicas are actually illuminated by a transmitted electron beam and the illusion of a lighted opaque surface arises from the heavy metal shadow which appears light when viewed as a negative.Stereography adds to the perspective provided by shadowing and reveals remarkable differences in elevation which would be unnoticed in single micrographs. This technique now seems essential to the proper interpretation of freeze etched replicas. It further aids in the detection of artifacts due to the electron density of the replica itself.