Molecular beam epitaxy conditions

Electrical Properties. Generally, deposited thin films have an electrical resistivity that is higher than that of the bulk material. This is often the result of the lower density and high surface-to-volume ratio in the film. In semiconductor films, the electron mobiHty and lifetime can be affected by the point defect concentration, which also affects electromigration. These effects are eliminated by depositing the film at low rates, high temperatures, and under very controUed conditions, such as are found in molecular beam epitaxy and vapor-phase epitaxy. 

Clearly, there are situations where we have to give up this assumption. A typical case is molecular beam epitaxy (MBE) (see [3,12-14] and [15-19]), where particles are shot onto the surface of a crystal rather than condensing slowly from a thermally equilibrated vapor-phase. In this case we will have to be very specific about all the experimental boundary conditions and... 

The proposed technique seems to be rather promising for the formation of electronic devices of extremely small sizes. In fact, its resolution is about 0.5-0.8 nm, which is comparable to that of molecular beam epitaxy. However, molecular beam epitaxy is a complicated and expensive technique. All the processes are carried out at 10 vacuum and repair extrapure materials. In the proposed technique, the layers are synthesized at normal conditions and, therefore, it is much less expansive. The presented results had demonstrated the possibility of the formation of superlattices with this technique. The next step will be the fabrication of devices based on these superlattices. To begin with, two types of devices wiU be focused on. The first will be a resonant tunneling diode. In this case the quantum weU will be surrounded by two quantum barriers. In the case of symmetrical structure, the resonant... 

High-vacuum dry-processes, such as chemical vapor deposition (CVD) and molecular beam epitaxy (MBE), have made it feasible to control precisely the thickness of metal oxide thin films. In these techniques, the preparative conditions like pressure and substrate temperature can be widely varied, and the elemental composition in individual atomic layers is controllable by sequential supply of precursor gases [1]. The dense, defect-less oxide films thus prepared are frequently used as underlayers of microelectronics devices. 

Although many reports are available on deposition performed at atmospheric pressure, low pressure operation is convenient in order to obtain satisfactory molar fractions of the precursor (of the order of 10 ) at relatively low (if possible less than 100°C) volatilization temperature, and also to achieve improved conformal coverage of the substrates. Only few investigations have been performed with varying deposition pressure."" It is worth noting that Ni(HL ) and NiCp have been decomposed in molecular beam epitaxy (MBE) conditions, but with a high carbon contamination for the latter." ... 

Molecular beam epitaxy (MBE) is really evaporation followed by condensation and reaction on a substrate, done under very clean, ultrahigh vacuum conditions at... 

Thin film science and technology is the deposition and characterization of layered structnres, typically less than a micron in thickness, which are tailored from the atomic scale upwards to achieve desired functional properties. Deposition is the synthesis and processing of thin films under controlled conditions of chemical processing. Chemical vapor deposition (CVD) and gas-phase molecular beam epitaxy (MBE) are two processes that allow control of the composition and structure of the films. Characterization is the instrumentation that use electrons, X-ray, and ion beams to probe the properties of the film. Epitaxial films of semiconductors are used for their electronic properties to emit light in the infrared (IR) and the ultraviolet rays. 

Physical methods, which include (a) a vapor phase condensation technique under ultra-high vacuum conditions (6), (b) mechanical milling (7), (c) laser dissipation (8), and (d) molecular-beam epitaxy (9). 

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