266 results about "Free carrier" patented technology

A thermal processing apparatus and method in which a first laser source, for example, a CO2 emitting at 10.6 μm is focused onto a silicon wafer as a line beam and a second laser source, for example, a GaAs laser bar emitting at 808 nm is focused onto the wafer as a larger beam surrounding the line beam. The two beams are scanned in synchronism in the direction of the narrow dimension of the line beam to create a narrow heating pulse from the line beam when activated by the larger beam. The energy of GaAs radiation is greater than the silicon bandgap energy and creates free carriers. The energy of the CO2 radiation is less than the silicon bandgap energy so silicon is otherwise transparent to it, but the long wavelength radiation is absorbed by the free carriers.

A thermal processing apparatus and method in which a first laser source, for example, a CO2 emitting at 10.6 μm is focused onto a silicon wafer as a line beam and a second laser source, for example, a GaAs laser bar emitting at 808 nm is focused onto the wafer as a larger beam surrounding the line beam. The two beams are scanned in synchronism in the direction of the narrow dimension of the line beam to create a narrow heating pulse from the line beam when activated by the larger beam. The energy of GaAs radiation is greater than the silicon bandgap energy and creates free carriers. The energy of the CO2 radiation is less than the silicon bandgap energy so silicon is otherwise transparent to it, but the long wavelength radiation is absorbed by the free carriers.

Apparatus for and methods of thermally processing undoped or lightly doped semiconductor wafers (30) that typically are not very absorptive of an annealing radiation beam (14) are disclosed. The apparatus (10) uses a relatively low power activating radiation beam (240) with a photon energy greater than the bandgap energy of the semiconductor substrate in order to generate free carriers (315) at and near the substrate surface (32). The free carriers so generated enhance the absorption by the substrate surface of the longer wavelength annealing radiation beam. The annealing radiation beam is thus able to rapidly heat the substrate surface and permit subsequent rapid cooling to obtain, for example, a high level of electrical activity (activation) of dopants (310) formed therein. The invention obviates the need to pre-heat the substrate in order to increase absorption of the annealing radiation beam when performing thermal processing.

Methods and specialized media adapted to the formation of a steady-state, non-equilibrium distribution of free carriers using mesoscopic classical confinement. Specialized media is silicon-based (e.g., crystalline silicon, amorphous silicon, silicon dioxide) and formed from mesoscopic sized particles embedded with a matrix of wide-bandgap material, such as silicon dioxide. An IR to visible light imaging system is implemented around the foregoing.

The present invention provides a silicon wave-guide (3), with a silicon oxide cladding (2, 4) on a silicon substrate (1). At predetermined positions along the length of the wave-guide, are created metal oxide semiconductor (MOS) structures. A poly-silicon, or any other conductive layer (5), is deposited and patterned above the upper cladding (4) and electrical contacts are made to the substrate (1), the silicon wave-guide (3), and the poly-silicon layer (5). Upon the application of a potential difference between at least two of the layers from the group comprising the substrate (1), the silicon wave-guide (3), and the poly-silicon layer (5), the free carrier concentration at the top and / or bottom layer of the silicon wave-guide (3) is changed by the electric field. The change in the electric field results in a change in the index of refraction, and the change in the index of refraction causes a change in the optical mode propagating in the waveguide (3). The propagation is controlled by controlling the changes in the electric field, which can be enhanced by localized changes in the optical properties of the wave-guide (3) induced by ion implantation (6) or trapping of photo-carriers.

A solution for designing and / or fabricating a structure including a quantum well and an adjacent barrier is provided. A target band discontinuity between the quantum well and the adjacent barrier is selected to coincide with an activation energy of a dopant for the quantum well and / or barrier. For example, a target valence band discontinuity can be selected such that a dopant energy level of a dopant in the adjacent barrier coincides with a valence energy band edge for the quantum well and / or a ground state energy for free carriers in a valence energy band for the quantum well. The quantum well and the adjacent barrier can be formed such that the actual band discontinuity corresponds to the target band discontinuity.

An optical mode converter comprising a slow wave electrode structure and including Schottky barriers for preventing an accumulation of free carriers in the optical waveguide region of the converter. The Schottky barriers are also used for suppressing higher order modes in the waveguide. Low refractive index insulators are used to allow efficient driving of the device without hindering the impedance or the microwave index of the optical mode converter. Two-photon absorption processes are eliminated through the use of a waveguide semiconductor material having a bandgap of at least twice the photon energy of the light beam propagating through the optical mode converter.

Nano-engineered structures are disclosed, incorporating nanowhiskers of high mobility conductivity and incorporating pn junctions. In one embodiment, a nanowhisker of a first semiconducting material has a first band gap, and an enclosure comprising at least one second material with a second band gap encloses said nanoelement along at least part of its length, the second material being doped to provide opposite conductivity type charge carriers in respective first and second regions along the length of the of the nanowhisker, whereby to create in the nanowhisker by transfer of charge carriers into the nanowhisker, corresponding first and second regions of opposite conductivity type charge carriers with a region depleted of free carriers therebetween. The doping of the enclosure material may be degenerate so as to create within the nanowhisker adjacent segments having very heavy modulation doping of opposite conductivity type analogous to the heavily doped regions of an Esaki diode. In another embodiment, a nanowhisker is surrounded by polymer material containing dopant material. A step of rapid thermal annealing causes the dopant material to diffuse into the nanowhisker. In a further embodiment, a nanowhisker has a heterojunction between two different intrinsic materials, and Fermi level pinning creates a pn junction at the interface without doping.

A semiconductor integrated circuit device according to the invention includes an N-type embedded diffusion region between a substrate and a first epitaxial layer in island regions serving as small signal section. The substrate and the first epitaxial layer are thus partitioned by the N-type embedded diffusion region having supply potential in the island regions serving as small signal section. This structure prevents the inflow of free carriers (electrons) generated from a power NPN transistor due to the back electromotive force of the motor into the small signal section, thus preventing the malfunction of the small signal section.

New circuit architecture for electro-optic modulator based on free-carrier dispersion effect is invented, in which the waveguide capacitor of the modulator is embed in the circuits and physically layout together with transistors, the switching of the modulator occurs in transistors, and as the result, the electro-optical modulation occurs in the waveguide capacitor. The invented modulator is not one physical device, it is actually a circuit. Several circuit design techniques are imported, leading to several new modulator circuits that have very high operation speed and very small power consumption. Several new waveguide capacitor structures are also invented that allow high efficient modulator circuits to be built.