Tadao Inuzuka

Growth of diamond thin films by electron assisted chemical vapor deposition

Diamond thin films have been formed by the newly proposed electron assisted chemical vapor deposition on SiC with a high growth rate (3∼5 μm/h). The obtained films have good crystallinity in the sense of electron and x‐ray diffraction. Vicker’s hardness of the films is about 9000 kg/mm2. The influence of the electron bombardment on the initial island density on the substrate surface and on the decomposition of the reactant gases (CH4 and H2) is discussed relating to the growth process of the films.

Epitaxial Growth of Diamond on Iridium

Epitaxial growth of diamond on iridium thin films was performed by direct-current plasma chemical vapor deposition with ion irradiation pretreatment of the substrate. Pyramidal epitaxial diamond particles with a number density of ~108 cm-2 were grown on the iridium film. The epitaxial relation is written as (100) diamond//(100) iridium and [001] diamond//[001] iridium. Tilting of the epitaxial relation, as occasionally observed for diamond on silicon or beta silicon carbide, is scarcely observed. Erosion,as observed for diamond on nickel substrates, is not observed. The effect of the ion irradiation of the substrate is discussed briefly.

Nucleation of Gold Deposits on Alkali-Halide Crystals

Nucleation of gold deposits on the cleavage surface of NaCl and KCl has been studied as a function of substrate temperature and incidence rate. Experimental results on vacuum cleaved surface indicate that selective nucleation occurs on imperfection sites such as point defects and impurities, and that random one occurs on defect-free surfaces at relatively higher deposition rate. The deposits on color-centered surfaces of NaCl produced by X-ray irradiation showed an increase of nucleation density compared with that on the normal cleavage surfaces and an enhancement of (100) parallel epitaxy at relatively lower substrate temperature. It appears that the controlled production of point defects has an important role in nucleation and growth. The nature of nucleation sites is discussed in connection with the epitaxial growth of deposits.

NUCLEATION DENSITY AND EPITAXY OF GOLD DEPOSITED ONTO COLOR‐CENTERED CLEAVAGE SURFACE OF ROCKSALT

The vacuum deposition of gold upon the color‐centered surface of NaCl produced by x‐ray irradiation is described. The increase of nucleation density and the enhancement of (100) parallel orientation are observed. It appeared that these findings in experimental results compared with the phenomena on the normal cleavage surface were attributable to the effects of point imperfections produced. A lowering of epitaxial temperature is also observed. The controlled production of imperfections on the surface by irradiation has a critical effect upon the nucleation and epitaxial growth.

Nucleation density of gold trapped by imperfections on the cleavage surface of sodium chloride

Abstract Nucleation of gold from the vapour phase on sodium chloride is studied as a function of substrate temperature and incidence rate. Special attentions are paid to the preparation of the substrate surface by vacuum cleaving and artificial damaging. Deposition onto the vacuum-cleaved surface indicates that surface imperfections are responsible for the selective nucleation. It appears that random nucleation occurs even on the perfect lattice sites at relatively higher deposition rates. The deposition onto a colour-centered surface produced by X-ray irradiation and a surface bombarded by electrons showed a remarkable increase in nucleation density compared with the normal cleaved one. Lowering of epitaxial temperature is also observed for deposits on the treated surface. The relationship between the increased nucleation density and the enhancement of (100) parallel growth is discussed.

Crystal surface effects on the nucleation and epitaxial growth of gold deposits from the vapour phase

Abstract Nucleation and epitaxial growth of gold deposits on the cleavage surfaces of alkali halide crystals have been studied as a function of substrate temperature and incidence rate. Experimental results on vacuum cleaved surfaces indicate that selective nucleation occurs on imperfection sites such as point defects and impurities, and that random nucleation occurs on defect-free surfaces at a relatively higher deposition rate. To study the effect of point defects on nucleation, crystal material irradiated by X-ray and electron beam is used as substrate. The deposits on surfaces of rock salt crystals with colour centres produced by X-ray irradiation showed an increase of nucleation density compared with that on the normal cleavage surfaces and an enhancement of (100) parallel epitaxy at relatively lower substrate temperature. It appears that the controlled production of point defects and their electrostatic nature might be important factors in nucleation and epitaxial growth from the vapour phase.

Continuous Observation of Initial Growth and Coalescence of Bismuth Deposits by In Situ Electron Microscopy

The vacuum deposition of bismuth on a thin substrate of molybdenum disulfide was carried out inside an electron microscope. Time sequences of the formation process of a thin film were recorded using a cine camera. Initial growth of deposits was studied as a function of substrate temperature. It is found that the linear dimension of particles increases nearly proportionally to the square root of deposition time in the range of substrate temperatures observed. At the temperature of about 150u2009°C, particles having a dimension less than 150 A, are liquid, and transformation from liquid to crystalline particles, as they grow larger, is also observed. The coalescence process of particles was recorded on cine films at relatively higher speeds. It is found that coalesced particles have, in general, a small projected area compared to the sum of areas of initial two particles. The mechanism of this process is discussed in connection with the theory of sintering as proposed by Pashley et al. [Phil. Mag. 10, 127 (1964)].