Implementations of the present disclosure generally relate to an improved vacuum processing system. In one implementation, the vacuum processing system includes a first transfer chamber coupling to at least one epitaxy process chamber, a second transfer chamber, a transition station disposed between the first transfer chamber and the second transfer chamber, a first plasma-cleaning chamber coupled to the second transfer chamber for removing oxides from a surface of a substrate, and a load lock chamber coupled to the second transfer chamber. The transition station connects to the first transfer chamber and the second transfer chamber, and the transition station includes a second plasma-cleaning chamber for removing carbon-containing contaminants from the surface of the substrate.

A gallium nitride substrate comprising a first main surface and a second main surface opposite thereto, wherein the first main surface is a non-polar or semi-polar plane, a dislocation density measured by a room-temperature cathode luminescence method in the first main surface is 1×10.sup.4 cm.sup.−2 or less, and an averaged dislocation density measured by a room-temperature cathode luminescence method in an optional square region sizing 250 μm×250 μm in the first main plan is 1×10.sup.6 cm.sup.−2 or less.

A gallium nitride substrate comprising a first main surface and a second main surface opposite thereto, wherein the first main surface is a non-polar or semi-polar plane, a dislocation density measured by a room-temperature cathode luminescence method in the first main surface is 1×10.sup.4 cm.sup.−2 or less, and an averaged dislocation density measured by a room-temperature cathode luminescence method in an optional square region sizing 250 μm×250 μm in the first main plan is 1×10.sup.6 cm.sup.−2 or less.

A window assembly heat transfer system is disclosed in which a window member has a selected transparency to monitored or sensed light wavelengths. One or more passages are provided in the window member for flowing a single-phase or two-phase heat transfer fluid, the passages being optically non-transparent to the monitored or sensed light wavelengths. A mechanism allows either evaporation or condensation of the fluid and/or balancing of a flow of the fluid within the passages. In one embodiment, the window assembly can be made by producing passages in a top surface of a first single plate, optionally producing passages in a bottom surface of a second single plate and bonding the top surface of the first plate to a bottom surface of a second single plate to form the window member with the passage or passages. In another embodiment, the window assembly can be made by providing a core around which the window member material is grown and thereafter removing the core to produce the passage or passages.

Provided are a method for preparing a vertical branched graphene comprising treating a pristine vertical graphene with an inert plasma in the absence of an introduced carbon source to develop a vertical branched graphene. The method may also include pre-treating a substrate surface with an inert plasma; depositing a pristine vertical graphene onto the substrate surface by contacting the substrate surface with a deposition plasma comprising a carbon source gas for a deposition period. Also provided are a vertical branched graphene attached to a substrate surface, the vertical branched graphene having a trunk portion extending from the substrate surface, said trunk possessing an increased degree of branching as the distance from the substrate surface increases; and a freestanding branched graphene with a proximal end and a distal end, the proximal end comprising a trunk portion, the trunk portion possessing and increased degree of branching as the distance from the proximal end increases and the distance to the distal end decreases.

A crystal can be formed using vapor deposition. In one set of embodiments, the crystal can be grown such that the crystal selectively grown along a particular surface at a relatively faster rate as compared to another surface. In another embodiment, the assist material may aid in transporting or depositing the vapor species of a constituent to surfaces of the crystal. In a further set of embodiments, the crystal can be vapor grown in the presence of an assist material that is attracted to or repelled from a particular location of the crystal to increase or reduce crystal growth rate at a region adjacent to the location. The position of the relatively locally greater net charge within the assist material may affect the crystal plane to which the assist material is attracted or repelled. An as-grown crystal may be achieved that has a predetermined geometric shape.

A crystal can be formed using vapor deposition. In one set of embodiments, the crystal can be grown such that the crystal selectively grown along a particular surface at a relatively faster rate as compared to another surface. In another embodiment, the assist material may aid in transporting or depositing the vapor species of a constituent to surfaces of the crystal. In a further set of embodiments, the crystal can be vapor grown in the presence of an assist material that is attracted to or repelled from a particular location of the crystal to increase or reduce crystal growth rate at a region adjacent to the location. The position of the relatively locally greater net charge within the assist material may affect the crystal plane to which the assist material is attracted or repelled. An as-grown crystal may be achieved that has a predetermined geometric shape.

A chemical vapor deposition (CVD) reactor includes a resonating cavity configured to receive microwaves. A microwave transparent window positioned in the resonating cavity separates the resonating cavity into an upper zone and a plasma zone. Microwaves entering the upper zone propagate through the microwave transparent window into the plasma zone. A substrate is disposed proximate a bottom of the plasma zone opposite the microwave transparent window. A ring structure, positioned around a perimeter of the substrate in the plasma zone, includes a lower section that extends from the bottom of the resonating cavity toward the microwave transparent window and an upper section on a side of the lower section opposite the bottom of the resonating cavity. The upper section extends radially toward a central axis of the ring structure. A method of microwave plasma CVD growth of a diamond film on the substrate is also disclosed.

Efficiency of producing polycrystalline silicon is improved. A silicon filament (11) is constituted by a rod-shaped member made of polycrystalline silicon. The polycrystalline silicon has an interstitial oxygen concentration of not less than 10 ppma and not more than 40 ppma. On a side surface, in a lengthwise direction, of the rod-shaped member, crystal grains each having a crystal grain size of not less than 1 mm are observed.

Efficiency of producing polycrystalline silicon is improved. A silicon filament (11) is constituted by a rod-shaped member made of polycrystalline silicon. The polycrystalline silicon has an interstitial oxygen concentration of not less than 10 ppma and not more than 40 ppma. On a side surface, in a lengthwise direction, of the rod-shaped member, crystal grains each having a crystal grain size of not less than 1 mm are observed.