| CPC C30B 29/42 (2013.01) [B32B 3/26 (2013.01); C30B 33/00 (2013.01); H01L 21/02052 (2013.01); H10D 62/85 (2025.01)] | 10 Claims |

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1. A gallium arsenide single crystal substrate comprising a main surface having a circular shape,
wherein the gallium arsenide single crystal substrate has a first integrated intensity ratio or a second integrated intensity ratio,
the first integrated intensity ratio and the second integrated intensity ratio are each obtained by determining a spectrum of a detected intensity of a 3d electron of each of arsenic and gallium with respect to binding energy of a photoelectron emitted to an outside of the gallium arsenide single crystal substrate based on X-ray photoelectron spectroscopy in which a center of the main surface is irradiated with X-rays under a condition of an incident X-ray energy of 150 eV and a photoelectron take-off angle of 85°,
the first integrated intensity ratio is a ratio of a sum of an integrated intensity of gallium element present as digallium monoxide and an integrated intensity of gallium element present as digallium trioxide to an integrated intensity of gallium element present as gallium arsenide and is 12 or less,
the second integrated intensity ratio is a ratio of the sum of the integrated intensity of gallium element present as digallium monoxide and the integrated intensity of gallium element present as digallium trioxide to a sum of an integrated intensity of arsenic element present as diarsenic pentoxide and an integrated intensity of arsenic element present as diarsenic trioxide and is 1.2 or less, and
the number of particles present on the main surface and each having a major axis of 0.16 μm or more is 2 or less per cm2 of the main surface.
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