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A real time observation of the growth of agglomerates of pyramidal crystallites of mercuric iodide on a porous glass surface using tapping mode atomic force microscopy is reported. Crystallites are observed to grow from the pores (5.0 nm diameter) onto the surface of the porous glass impregnated with mercuric iodide. Immediately after fracturing the impregnated porous glasses, topographical images reveal a surface with a root mean square roughness of 75–130 nm over a 5 μm×5 μm area, which is typical for surfaces of fractured porous glass. After 3 h, 60–90 nm pyramidal structures with a high aspect ratio (pyramid base to height) begin to appear on the surface. Some of the pyramidal structures agglometrate and form structures much larger and higher than the surrounding ones. The bottom of some of these agglomerated pyramids form equilateral triangles with dimensions of 300–500 nm, exhibiting a preferred orientation on the surface. 6 h after fracturing, micrometer‐size crystallites are observed. Most of the pyramidal structures are no longer observed and mostly needlelike features are covering the surface. Step heights consistent with multiples of the c axis of α‐mercuric ioide are observed on the micrometer‐sized crystallites. Some pyramidal structures are observed between the large crystallites, with sizes comparable to the early stage pyramidal structures. Raman and electronic spectra are also reported for mercuric iodide confined in porous glasses. The Raman spectra have peaks located at 39 and 141 cm−1, indicating that the confined mercuric iodide is stabilized in the yellow, orthorhombic (β phase) at room temperature. Confinement of mercuric iodide in pores with radii smaller than 3.75 nm results in the appearance of a new band at 145 cm−1 in the Raman spectra, suggesting the presence of a new or modified β phase of mercuric iodide. Further evidence supporting the presence of a new phase of mercuric iodide is found in the electronic spectra where an energy gap of 2.7 eV is observed, and lies between the energy gaps of the red, tetragonal, α phase (2.2 eV) and the yellow, orthorhombic β phase (3.1 eV) of mercuric iodide. The atomic force microscopy measurements provide a unique method for real time monitoring of the crystal growth and morphology changes of nanocrystalline mercuric iodide, while the spectroscopy provides insight to the phonon structure and energy gaps of the confined material.

Mercuric iodide HgI2 is a layered material consisting of alternating sequences of I–Hg–I atoms stacked along the c axis and bonded through van der Waals forces. The dynamics of surface structure modifications of a freshly cleaved crystal of α‐HgI2 have been investigated by tapping mode atomic force microscopy. Layer‐by‐layer removal of HgI2 is observed and is attributed to the tapping tip interactions with the relatively soft mercuric iodide surface and also to the relatively high vapor pressure of HgI2. The step heights between the layers are found to be either 6 or 12 A corresponding to one or two layers of HgI4 tetrahedra. The effect of the tip modification is characterized by continuously scanning the same area for 1 h (41 scans) which produce craters ∼120 nm in depth. Three consecutive scans separated by 1 h intervals and imaged in the same area with a minimized tapping force reveal the effects of evaporation and the intrinsic instability of this surface under ambient conditions. Comparison of the images collected with 1 h intervals between consecutive scans and the 41 consecutive scans with no delay allows for decoupling the evaporation and tip induced etching processes on the (001) surface of HgI2. Friction force images revealed two distinct areas with different friction on the (001) surface. The area of high friction was found to have an atomically resolved periodicity of 4.4 A which corresponds to the lattice spacing of the a or b planes. The areas of low friction exhibited a periodicity of 5.5 A and this spacing was attributed to a defect induced distortion of the a or b lattice constant.

Atomic force microscopy was used to characterize the surface of semi‐insulating bismuth tri‐iodide, lead iodide, and mercuric iodide crystals. These heavy metal iodides belong to a unique class of materials that provide a wide range of interesting problems that can be studied by atomic force microscopy. They have relatively high vapor pressures and cannot be examined noninvasively in vacuum conditions, such as by electron microscopy. Mercuric, bismuth, and lead iodide are layered materials with van der Waals bonding along the c axis and therefore, like mica, can be easily cleaved to provide fresh atomically flat crystalline surfaces to study. These crystals are soft with a high degree of plasticity and, as a result, the surfaces are easily modified by the cantilever tip. They demonstrate reactivity in ambient air at the surfaces as well as within the van der Waals gap. Freshly cleaved surfaces were examined and it was found that single and multiple atomic layers were easily displaced on the cleaved surfaces in all of the crystals when scanned in both contact and modulated contact mode. The effects of cantilever induced modifications of the surfaces of mercuric, lead, and bismuth iodide were studied by atomic force microscopy and their properties are discussed.

Ion implantation of gold into sapphire followed by annealing at 1100 °C leads to the formation of metal colloids. We report on the atomic force microscopy (AFM), infrared reflectance, and optical spectra for Au implanted in sapphire. The presence of the metal colloids is revealed in the optical spectra by the appearance of an absorption at 547.5 nm for the annealed sample, which we attribute to the surface plasmon resonance of Au colloids. The infrared spectra indicate that annealing Au‐implanted sapphire at 1100 °C relaxes most of the ion‐induced damage in the crystal. Tapping mode AFM has been applied to image the Au colloids embedded in the sapphire matrix. Colloids ranging in size from 10 to 30 nm were observed by AFM measurements. The shape of the colloids appear to be predominantly spherical.

Atomic force microscopy was used to study the surfaces of mercuric iodide crystals at ambient. Various surface conditions were examined, including as‐grown (001), (110), and (013) faces, and cleaved, chemically etched, vacuum etched, and aged (001) surfaces. As‐grown (001) faces show a terraced structure and are smoother than as‐grown (110) faces. Freshly cleaved surfaces exhibit a terraced structure, with riser heights corresponding to multiples of the c‐lattice constant. All surfaces become progressively pitted and rougher by vacuum treatment or chemical etching. Defects identified as pits or hillocks with dimensions of the order of 100 nanometers were also observed, and surface roughness values were obtained for quantitative characterization of the various treatments.

The study of the crystal surface morphology of CdZnTe is important for the understanding of the fundamentals of crystal growth in order to improve the crystal quality which is essential in applications such as substrates for epitaxy or performance of devices, i.e., room temperature nuclear spectrometers. We present here a first atomic force microscopy study on CdZnTe. Cleaved (110) surfaces were imaged in the ambient and an atomic layer step structure was revealed. The effects of thermal annealing on the atomic steps together with Te precipitation along these steps are discussed in terms of deformation due to stress relief and the diffusion of tellurium precipitates.