This paper reports a study of two types of silicon based nanostructures prospective for applications in photonics. The first ones are Ge/Si(001) structures forming at room temperature and reconstructing after annealing at 600°C. Germanium, being deposited from a molecular beam at room temperature on the Si(001) surface, forms a thin granular film composed of Ge particles with sizes of a few nanometers. A characteristic feature of these films is that they demonstrate signs of the 2 x 1 structure in their RHEED patterns. After short-term annealing at 600°C under the closed system conditions, the granular films reconstruct to heterostructures consisting of a Ge wetting layer and oval clusters of Ge. A mixed type c(4x2) + p(2x2) reconstruction typical to the low-temperature MBE (Tgr < 600°C) forms on the wetting layer. Long-term annealing of granular films at the same conditions results in formation of c(4x2)-reconstructed wetting layer typical to high-temperature MBE (Tgr < 600°C) and huge clusters of Ge. The other type of the studied nanostructures is based on Pt silicides. This class of materials is one of the friendliest to silicon technology. But as silicide film thickness reaches a few nanometers, low resistivity becomes of primary importance. Pt3Si has the lowest sheet resistance among the Pt silicides. However, the development of a process of thin Pt3Si films formation is a challenging task. This paper describes formation of a thin Pt3Si/Pt2Si structures at room temperature on poly-Si films. Special attention is paid upon formation of poly-Si and amorphous Si films on Si3N4 substrates at low temperatures.
Growth and characterization of Ge/Si(001) heterostructures with dense chains of stacked Ge quantum dots are reported. Ge hut nucleation and growth at low temperatures is discussed on the basis of results obtained by high resolution scanning tunneling microscopy and in-situ reflected high-energy electron diffraction. Atomic-level models of nucleating and growing huts are proposed. Data of high resolution transmission electron microscopy are presented focusing on long chains of Ge quantum dots. New photovoltaic quantum dot infrared photodetectors are proposed.
We present results of STM investigation of surface of the Si epitaxial layers deposited on different Si(001) vicinal substrates at the step flow growth mode. We have observed two types of the growth defects looking like meandering or pits. The way of the defects formation does not depend on the direction of tilt of the Si(001) substrate. The formation of the defects is connected with particularities of the processes of the movement onto terraces and attachment to the step edge of Si ad-atoms during growth. We suppose that Ehrlich-Schwoebel and kink Ehrlich-Schwoebel effects drive irregular growth of the monoatomic steps during Si/Si(001) epitaxy. Process of the defect formation starts when the deep kink confined by two Sa steps appears on the step edge. Next difference between growth rate of the Sa and Sb steps results in formation of the area with other morphology.