Axt, Inc.

Beijing Tongmei Xtal Technology Co., Ltd.

Rajaram Shetty

Weiguo Liu

Morris Young

Yuanli Wang

Sung-Nee George Chu

Yvonne Zhou

Wei Zhang

Methods and wafers for vertical gradient freeze 8 inch gallium arsenide (GaAs) substrates. In disclosed examples, vertical gradient freeze systems for forming gallium arsenide (GaAs) substrates having silicon as a dopant, the system includes a crucible to contain a GaAs liquid melt and seed material during a formation process; one or more heating coils arranged in a plurality of heating zones; and a pedestal to move relative to the crucible, the system operable to control heating of the plurality of heating zones and movement of the pedestal to form a single crystal GaAs substrate.

Method and system for vertical gradient freeze 8 inch gallium arsenide substrates

A germanium single-crystal wafer comprises silicon with an atomic concentration of from 3×10atoms/cc to 10×10atoms/cc, boron with an atomic concentration of from 1×10atoms/cc to 10×10atoms/cc, and gallium with an atomic concentration of from 1×10atoms/cc to 10×10atoms/cc. Further provided are a method for preparing the germanium single-crystal wafer, a method for preparing a germanium single-crystal ingot, and the use of the germanium single-crystal wafer for increasing the open-circuit voltage of a solar cell. The germanium single-crystal wafer has an improved electrical property in that it has a smaller difference in resistivity and carrier concentration.

Germanium single-crystal wafer, method for preparing germanium single-crystal wafer, method for preparing crystal bar, and use of single-crystal wafer

Methods and systems for low etch pit density gallium arsenide crystals with boron dopant may include a gallium arsenide single crystal wafer having boron as a dopant, an etch pit density of less than 500 cm, and optical absorption of 6 cmor less at 940 nm. The wafer may have an etch pit density of less than 200 cm. The wafer may have a diameter of 6 inches or greater. The wafer may have a boron concentration between 1×10cmand 2×10cm. The wafer may have a thickness of 300 μm or greater. Optoelectronic devices may be formed on a first surface of the wafer, which may be diced into a plurality of die and optical signals from an optoelectronic device on one side of one of the die may be communicated out a second side of the die opposite to the one side.

Low etch pit density gallium arsenide crystals with boron dopant

Methods and systems for low etch pit density 6 inch semi-insulating gallium arsenide wafers may include a semi-insulating gallium arsenide single crystal wafer having a diameter of 6 inches or greater without intentional dopants for reducing dislocation density, an etch pit density of less than 1000 cm, and a resistivity of 1×10Ω-cm or more. The wafer may have an optical absorption of less than 5 cmless than 4 cmor less than 3 cmat 940 nm wavelength. The wafer may have a carrier mobility of 3000 cm/V-sec or higher. The wafer may have a thickness of 500 μm or greater. Electronic devices may be formed on a first surface of the wafer. The wafer may have a carrier concentration of 1.1×10cmor less.

Low etch pit density 6 inch semi-insulating gallium arsenide wafers

Methods and systems for low etch pit density 6 inch semi-insulating gallium arsenide wafers may include a semi-insulating gallium arsenide single crystal wafer having a diameter of 6 inches or greater without intentional dopants for reducing dislocation density, an etch pit density of less than 1000 cm, and a resistivity of 1&#xd7;10&#x3a9;-cm or more. The wafer may have an optical absorption of less than 5 cmless than 4 cmor less than 3 cmat 940 nm wavelength. The wafer may have a carrier mobility of 3000 cm/V-sec or higher. The wafer may have a thickness of 500 &#x3bc;m or greater. Electronic devices may be formed on a first surface of the wafer. The wafer may have a carrier concentration of 1.1&#xd7;10cmor less.

A monocrystalline germanium wafer that increases the open-circuit voltage of multijunction solar cells, a method for preparing the monocrystalline germanium wafer and a method for preparing an ingot from which the monocrystalline germanium wafer is prepared. The monocrystalline germanium wafer that increases the open-circuit voltage of the bottom cell of multijunction solar cells is prepared by adjusting the amounts of the co-dopants silicon and gallium in the monocrystalline germanium wafer, the ratio of silicon to gallium in the preparation of the monocrystalline germanium.

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Fremont, CA, United States of America

Rajaram Shetty