In developing functional materials, most people are concerned with their characteristics like chemical reactivity, durability, adhesion, electrical properties, optical properties, corrosion-resistance and compatibility, etc. Particularly, the surface properties of materials are directly related with these concerns. For example, during the semiconductors manufacturing process, even the lowest amount of contamination of foreign objects on the surface may cause the product's quality fail. Thus, surface analysis is essential not only for the development of new surfaces with high functionality, but also for helping materials with high functions properly exhibit their functionality.
Surface analysis is comprehensive technology based on ultra-high vacuum, electronic ion optics, weak signal detection, and complicated computer technology. By using a beam of particles or some means as probes, such as electrons, ions, photons, or heat, to test the surface of the sample, the elemental composition, morphology and topography information, as well as structure and energy state within only a few atomic layers can be analyzed. At Alfa Chemistry, we specialize in surface, near surface and interface analysis across a wide range of sample types.
To understand the properties and reactivity of a surface, the following information is required: the physical topography, the chemical composition, the chemical structure, the atomic structure, the electronic state and a detailed description of bonding of molecules at the surface. No one technique can provide all these different pieces of information. A full investigation of a surface phenomenon will always require several techniques:
XPS/ESCA is a technique which analyzes the elements existing on sample surface, chemical composition, and electron binding energies by irradiating x-rays on the sample surface, and measuring the kinetic energy of the photoelectrons emitted from the sample surface. It can be used for the surface analysis of various materials whether they are organic or inorganic.
Basically, the principle of AES is very similar to the XPS/ESCA except that a focused keV electron beam may be used to bombard the surface. AES is characterized by extremely high spatial resolution, which has been mainly used in the observation of metal and semiconductor surfaces.
TOF-SIMS is a technique in which a beam of high energy (keV) primary ions bombard the surface while secondary atomic and cluster ions are emitted and separated with a mass spectrometer using the difference in time-of-flight. This technique can obtain information of elements or molecular species within 1 nm on the sample surface at a very high detection sensitivity.
ISS is a technique in which an ion beam bombards the surface and is scattered from the atoms in the surface. The scattering angles and energies are measured and used to compute the chemical composition and surface structure of the sample target. It is often used in the analysis and research of various materials such as metals, alloys, semiconductors, insulators, and polymers.
SEM is an electron microscope that produces high-resolution and high depth-of-field images of the sample surface by scanning with a focused beam of electrons. It can be used for surface (topography) imaging, particles characterization and elemental microanalysis (when connected with an auxiliary Energy Dispersive X-ray Spectroscopy (EDS) detector).
TEM is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. It can be used to study the growth of layers, chemical composition and defects in semiconductor components. High resolution TEM (HRTEM) can be used to analyze the quality, shape, size and density of quantum wells, wires and dots.
AFM is similar to scanning tunneling microscope (STM) but applicable to non-conducting surfaces. It is capable of measuring surface topography, quantifying surface roughness, and providing quantitative measurements of feature sizes. Furthermore, some advanced AFM modes expand its application for the qualitative measuring other properties, such as adhesion, modulus, dopant distribution, conductivity and surface potential, etc.
RHEED is a technique used to characterize the surface structure of crystalline materials with high energy electrons (about 10 keV-30 keV) diffracting the crystal. One of the important applications of RHEED is to observe the growth of thin films. In addition, it can also quantitatively obtain the data that the surface lattice is affected by factors such as substrate or temperature.
Alfa Chemistry is committed to manufacturing and providing raw materials related to alternative energy industry. When surface information or surface testing is needed, we determine to select the most appropriate analytical approach to help you obtain the best results. Alfa Chemistry employ different surface analysis and characterization techniques, striving to solve issues associated with surface coverage, molecular structure, contamination, and functionalization. Please do not hesitate to contact us for more detailed information about our analytical services, we will answer you as soon as possible.