US 2023/0407522 A1 · LOW ETCH PIT DENSITY 6 INCH SEMI-INSULATING GALLIUM ARSENIDE WAFERS

Abstract

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−2, and a resistivity of 1×107 Ω-cm or more. The wafer may have an optical absorption of less than 5 cm−1 less than 4 cm−1 or less than 3 cm−1 at 940 nm wavelength. The wafer may have a carrier mobility of 3000 cm2/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 1.1×107 cm−3 or less.

Claims20

Dependent claims

A method for forming single crystal gallium arsenide substrates, the method comprising:

sealing charge material comprising polycrystalline gallium arsenide, a gallium arsenide seed crystal, B2O3 encapsulant, and carbon in a crucible;
sealing the crucible in a quartz ampoule;
performing a vertical gradient freeze crystal growth process by heating the ampoule using a multi-zone heating system to progressively melt the charge material until a portion of the seed crystal is melted;
starting growth from the partially melted seed by implementing a controlled cooling of the multi-zone heating system at a rate of 0.1 to 2 degree C./hour;
applying a temperature gradient of between 0.2 to 5 C/cm at a melt-crystal interface;
and
maintaining a ratio of 1.0 to 4 between a temperature gradient above the melt-crystal interface to a temperature gradient below the melt-crystal interface in the multi-zone heating system to form a solidified gallium arsenide crystal.

4 more elements

Dependencies are inferred from the claim text.

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

Life of this patent

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

Life of this patent

Abstract

Claims20