Group iii-v compound semiconductor substrate and group iii-v compound semiconductor substrate with epitaxial layer

A group III-V compound semiconductor substrate being an indium phosphide substrate, the group III-V compound semiconductor substrate comprising particles of greater than or equal to 0.079 μm in particle size at less than or equal to 20 particles/cm2 on a main surface.

A group III-V compound semiconductor substrate being a semi-insulating indium phosphide substrate, wherein

• the group III-V compound semiconductor substrate comprises particles of greater than or equal to 0.19 μm in particle size at less than or equal to 0.22 particles/cm2 on a main surface, the main surface is coated with a protective film, and
• the protective film comprises a surfactant, and has a thickness of greater than or equal to 0.3 nm and less than or equal to 3 nm.

A group III-V compound semiconductor substrate being a semi- insulating indium phosphide substrate, wherein

• the group III-V compound semiconductor substrate comprises particles of greater than or equal to 0.079 μm in particle size at less than or equal to 20 particles/cm2 on a main surface,
• the main surface is coated with a protective film, and
• the protective film comprises a surfactant, and has a thickness of greater than or equal to 0.3 nm and less than or equal to 3 nm.

A group III-V compound semiconductor substrate being a gallium arsenide substrate, the group III-V compound semiconductor substrate comprising particles of greater than or equal to 0.079 μm in particle size at less than or equal to 1.0 particle/cm2 on a main surface.

An epitaxial layer-attached group III-V compound semiconductor substrate comprising a group III-V compound semiconductor substrate, and an epitaxial layer disposed on the main surface of the group III-V compound semiconductor substrate, the group III-V compound semiconductor substrate being a semi-insulating gallium arsenide substrate, comprising particles of greater than or equal to 0.079 μm in particle size at less than or equal to 12 particles/cm2 on a main surface, and comprising light point defects of greater than or equal to 3.0 μm in circle-equivalent diameter at less than or equal to 10 defects/cm2 on the main surface in a case where the epitaxial layer has a thickness of 5 μm.