Electron emissions from single-crystalline diamond surfaces by internally exciting electrons from the valence to conduction bands have been investigated. Monte Carlo simulations have been employed to estimate the impact ionization rates of carriers in diamond under high electric fields up to 1107V/cm. The calculations demonstrate substantial impact ionization rates which rapidly increase with increasing electric fields above 8105V/cm. Highly efficient electron emissions with high emission current efficiencies of approximate unity have been attained from a MIS-type diamond layered structure that are composed of heavily ion-implanted buried layer (M), undoped diamond (I) and hydrogenated p-type diamond (S) with an emission surface of a negative electron affinity. The highly efficient emission mechanism is discussed in relation to the field excitation of electrons from the valence band to the conduction band in the undoped diamond layer and the carrier transport to the diamond surface.

Microcrystalline silicon embedded in silicon oxide has been prepared by means of a wet oxidation of porous silicon (PS) anodically produced from degenerate Si wafers in a HF solution. As the oxidation proceeded, optical absorptions of the PS specimen in the visible light region shifted obviously to the higher energy side. Visible light emission from the oxidized specimen was observed at room temperature with photoexcitation by a He-Cd laser while the as-prepared specimen emitted no visible lights. These results are discussed in relation to the quantum size effect of the microcrystalline silicon confined in the oxide matrix as well as visible emissions from as-prepared specimens produced from non-degenerate Si wafers.

Thin Si films grown on anodized porous silicon have been characterized using a high-energy ion scattering technique with related simulations of MeV ions in solids. It turned out that the simulations are necessary and very usuful for quantitative and nondestractive analysis of thin films with thicknesses less than 100 nm. In the case of the epitaxial Si films examined, it is often insufficient for the characterization of crystalline quality to measure only the channeling minimum yield, and therefore, it is emphasized that angular scans over the critical angle in the vicinity of a channeling direction must be performed for the analysis of possible imperfections in thin films. The possible imperfections observed in the epitaxial specimen are treated quantitatively.