Semiconductors are materials with electrical conductivities between that of a conductor such as copper and an insulator such as glass, but their true value in electronic devices lies in the ability of their conductivity to be easily manipulated. Current conduction in a semiconductor occurs due to the movement of charge carriers: free electrons carry negative charge, while the spaces left behind when electrons move, often termed 'holes', carry positive charge. The inherent electrical properties of a semiconducting material can be manipulated by doping the material with impurities, which greatly increases the number of charge carriers available to conduct a current.
Semiconductor materials may be doped to be intrinsically n-type, having an excess of negative charge carriers, or p-type, having an excess of positive charge carriers. When doped semiconductors contact semiconductors of a different type, charge carriers become depleted in the region of this p-n junction. This depletion region is rectifying: it has the unique property of allowing current to flow only in one direction. This property is absolutely necessary to the operation of diodes and transistors. Additionally, the conductivity of a semiconductor can change on short timescales due to external conditions such as exposure to light or heat, the presence of an electrical or magnetic field, or mechanical deformation of its crystal structure. The effect of electrical fields on semiconductor conductivity is exploited in field-effect transistors, and sensitivity to other inputs allows the production of semiconductor-based sensors and photovoltaic devices.
Applications
PRODUCTS
Single Element Semiconductors, Source Metals & Dopants
Ultra High Purity Silicon & Germanium
Oxide Semiconductors
Halide Semiconductors
Antimonides
Arsenides
Nitrides
Phosphides
Selenides
Sulfides
Tellurides
Complex Compound Semiconductors
Quantum Dots
Boats
Crucibles
ATT supplies semiconductors and materials for the production of semiconductors in a wide variety of forms. These include single-crystal and polycrystalline bulk materials, finished semiconductor wafers, organometallic deposition precursors, oxide and ceramic dielectric materials, and numerous types of sputtering targets.
From bare wafer to finished chip, there are hundreds of special process steps, such as oxidation, spattering, lithography, etching, ion implantation and packaging, etc. in the process. Semiconductor raw materials are used in every link of integrated circuit production. The materials used in wafer manufacturing include silicon wafers, photoresist, photoresist reagents, wet electronic chemicals, electronic gases, CMP polishing materials, and target materials, etc. In terms of market share, among all these wafer manufacturing materials, silicon wafers account for the largest market, about 33%, followed by electronic gases, photolithography machines and supporting reagents. Chip packaging materials include packaging substrate, lead frame, resin, bonding wire, tin ball, and plating solution, etc. At the same time, similar wet electronic chemicals contain various kinds of reagents such as acid and alkali, and there are as many as hundreds of fine molecule industries. From the perspective of market share, among semiconductor packaging materials, packaging substrate accounts for the largest proportion (about 40%), followed by lead frame and bonding line.