The direct imaging of atomic structure in solids has become increasingly easier to accomplish with modern transmission electron microscopes, many of which have an information retrieval limit near 0.2nm point resolution. Achieving better resolution, particularly with any useful range of specimen tilting, requires a major design effort. This presentation describes the new Atomic Resolution Microscope (ARM), recently put into operation at the Lawrence Berkeley Laboratory. Capable of 0.18nm or better “interpretable” resolution over a voltage range of 400 kV to 1000kV with ± 40° biaxial specimen tilting, the ARM features a number of new electron-optical and microprocessor-control designs. These will be highlighted, and its atomic resolution performance demonstrated for a selection of inorganic crystals.

Analytical electron microscopy techniques comprising imaging, chemical analysis and microdiffraction are described together with details of the instrumentation required. Using the analytical electron microscope (AEM), the materials scientist can gain combined chemical and crystallographic information with a spatial resolution and sensitivity not available in other imaging instruments. Examples of the application of the AEM to determine solute distribution and crystal structure data are given.

Some applications of the computer for the electron microscope, in three major areas - 1) control of the microscope,2) image processing, and 3) structure Analysis - are discussed in the present paper.

Elemental microanalysis, using x-rays and electron energy loss scattering, has been shown to be possible with electron beam probe sizes down to 0.5nm. This paper will discuss some practical problems, such as specimen drift, signal magnitude, and probe-specimen interaction when the probe is made very small. These problems have arisen in two studies: 1) an investigation of as segregation in poly-crystalline Si and 2) imaging of metal spheres with surface and bulk plasmon inelastic scattering.

A time shared television digital image processing system has been developed for on-line electron microscopy and uses a large mainframe computer. The main component of the system is a digital television frame store which has many standard features for digital analysis such as: digitization, zoom and pan, arithmetic and Boolean processors, alphanumeric generators and so on. Images can be acquired at atomic resolution from a TEM, analyzed in real time and hard copy slides made under full computer control. A full range of computer software has been developed or modified from existing software and is generally compatible with IBM Fortran compilers. Some of the areas where extensive menu driven software has been developed are: particle size and feature analysis, algebraic and geometric image manipulations, Fourier analysis, digitization and process control, image contrast correction, text processing, etc. A number of applications areas have been explored which include: the structure of Si/SiO2 interfaces; nucleation of Au on rocksalt; the formation of hexatic structures from amorphous phases under shear, tension and compression; analysis of atomic surface structure and image motion and the analysis of field ion micrographs of amorphous structures. Several of these areas will be discussed in the context of image processing and materials characterization.

A new 400 kV electron microscope has been developed. It can combine high resolution (HR) image observation and convergent beam diffraction (CBD) analysis. The instrument is provided with a specimen height control (Z-control) system to get a wide range of illumination angles. In HR image observation, a resolving power of 0.18 nm is confirmed by ODM. Illumination angle of a converged beam can be changed from 1.0 mrad. to more than 10 mrad. using the Z-control system. Specimen height control is a very useful method to combine HR observation and CBD analysis.

The 200 kV electron microscope has been extensively utilized as a high grade model for diversified applications. This paper reports image resolution available at present with the Hitachi 200 kV Electron Microscope Model H-800 and possible techniques for improving present resolution limit which depends on the aberrations of objective lens.

The past decade has seen the evolution of the Philips TEM from a “microscope”to an integrated microanalytical system. A current example of this trend is the EM 420*, an instrument whose design concepts are reflected in the most recently offered TEM, the compact, high kV, high resolution EM430.

The orientation dependence of characteristic x-ray emissions have been used to determine specific site occupations of Rare Earth additions in epitaxially grown films of Y1.7Sm0.6 Lu0.7Fe12.A.theoretical formulation based on the assumption of highly localiszed inner shell excitations was used not only to oredict specific site sensitive orientations, but also to refine experimentally observed data employing a constrained least squares analysis to give probabilities for the occupation of the RE additions in the different crystallographic sites. Thus, it has been shown that in this compound the preference for the RE additions is a predominantly octahedral occupation with a probability ≳95%. Some of theassumptions and limitations of the technique have also been discussed.

Most solar silicon is grown in the form of cast ingots, e.g. HEM, Silso and UCP or in the form of thin continous ribbons, e.g. FFG, RTR and Web. HEM and EFG will be considered as representative example of each catagory.

A simple ratio technique using the phenomenon of electron channeling can be used to measure the substitutional concentrations of dopants in semiconductors on a submicron scale.A comparison was made between electron and ion channeling measurements on Si-Sb alloy samples having a range of nonsubstitutional fractions of Sb.Good agreement was obtained but both measurements indicated considerably more nonsubstitutional dopant than could be accounted for by precipitates observed in electron micrographs. The discrepancy can be explained if the precipitates are coherent in the early stages of growth and have their planes located interstitially with respect to the Si planes. The sensitivity of the electron channeling measurements to the implantation profile was investigated and found to be small.The determination of local dopant profiles in the electron microscope is described.

Small defects with habit parallel to {100} and {311} matrix planes were observed using high resolution transmission electron microscopy (HREM) within 100 nm from the Si-Si02 interfaces after one step oxidation in dry O2 at 900°C, 1000°C and 1150°C of Czochralski (CZ) grown [100] p type boron doped, 1.5 − 20 Ω cm Si wafers with concentrations of oxygen1.4 × 10 18cm−3 and carbon 4. − 10. × 10 16 cm−3.The defects were less than 10 nm wide and I nm thick. The {100} and {311} defect are interpreted tentatively as thin silica plateletes and {311} stacking faults respectively. Distribution of defects near the interface was random although their density appeared to be lower for higher oxidation temperatures. It is not yet clear whether the defects were formed during the oxidation treatments or were present near the surfaces of the asreceived wafers.

EBIC images of an HEM solar cell display extensive spatial innomogenieties in the production of short-circuit current. TEM imaging reveals a variety of morphologies having dimensions on the order of 10 Um embedded in the material.Correlation of a region with high current collection to one or these distinct morphological regions suggests that segregation or B is responsible for the EBIC contrast.

Surface sensitive transmission electron microscopy (SSTEM) and reflection electron microscopy (REM) have been used to analyze the Si (111) 1×1 → 7×7 surface reconstruction. The SSTEM and transmission electron diffraction results for the Si (111) 7×7 surface are interpreted using several possible “surface dislocation” models. The SSTEM and REM techniques have also been applied to the GaAs (100) MBE deposited surfaces. The rough surface topography for the c(4×4) reconstructed surface is attributed to surface steps motions and bunching upon interruption of the MBE deposition.

This paper reviews recent progress in understanding the role of vacancies (V) and self-interstitials (I) in self and impurity diffusion in Si. Surface oxidation perturbs the thermal equilibrium concentration of point defects and analyses of the resulting effects on dopant diffusion showed that both V and I are present. Developments in experimental and theoretical works on Au diffusion in Si yielded a determination of the I-component and an estimate of the V-component of the Si self-diffusion coefficient. It is hoped that the I and V thermal equilibrium concentrations may be determined in the near future.A number of important physical aspects of the anomalous diffusion of P are now understood but a basically satisfactory model may need further work.

Cross-sectional observations of interface structures at high magnification by TEM and STEM offer excellent lateral and depth resolution which are not available by other analytical techniques. This technique has recently been applied by the author to study metal/GaAs contacts and MBE-grown semiconductor heterojunctions. Specific observations on alloyed Au-Ni-Ge/GaAs and Pd/GaAs interfaces and on epitaxially grown Ge-GaAs and AlAs-GaAs superlattice structures are reviewed in this paper. The high spatial resolution of the energy dispersive x-ray analysis performed in a STEM is most useful in the studies of complicated metal/ GaAs interfacial reactions. However, to resolve on an atomic scale the compositional profile across a heterojunction, one has to rely on diffraction technique. The detailed analyses of these interfacial reactions and structures are shown to be essential to the understanding and control of the electronic behavior associated with these interfaces.

The process of oxygen precipitation in Czochralski silicon materials has been studied using high resolution transmission electron microscopy. The resulting structure depends strongly on the thermal history of the material. The initial stages of precipitation involve the formation of clusters exhibiting strain fields which are coherent and isotropic at intermediate temperatures (∼7000°C). Incoherent defects are formed when the interstitial oxygen precipitates into substitutional sites in the silicon lattice. For long-time anneals, the quasi-equilibrium defect structure ranges from needle-like coesite (450–600°C), silica platelets (600–1000°C) to polyhedral silica precipitates (900–1200°C).

Boron-doped microcrystalline (μc) silicon films produced by rf glow discharge from dilute (1%) mixtures of SiH4 in H2 show a critical dependence of conductivity on deposition conditions. The dark conductivity was related to the microscopic features using electron microscopy. The μc−Si:H films contain clusters of crystallites embedded in an amorphous matrix. The size of the crystalline clusters is typically 0.2 μm in diameter, and the size of the individual crystallites is about 2.5 nm. Electron micrographs of samples prepared at substrate temperatures Ts=135°C, 150°C, 165°C, and 180°C show that the number of crystalline clusters increases with Tsup to 165°C. At Ts=180°C, the crystallites completely disappear. When the concentration of SiH4 in H2 is decreased to 0.25%, the microstructure shows a high density of crystallites with no apparent clustering.

Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were performed to study the interfacial reactions of Ni/GaAs contact system as a result of isothermal annealing and two step annealing. Ni2GaAs was observed to exhibit preferred orientation relationships with respect to GaAs substrate after 300–350°C annealing. The compound decomposed to NiAs and Ga-compounds after 400°C annealing. NiAs was also found to grow preferentially on GaAs. The step annealing was found to be ineffective in varying the morphological structure of interface.

Defects in InGaAsP and InGaP crystals lattice-matched to (001)-oriented GaAs substrate successfully grown by liquid phase epitaxy, have been investigated by TEM and STEM/EDX. Typical defects observed by TEM are composition-modulated structures, dislocation loops, non-structural microdefects, and stacking faults.