Gallium arsenide single crystal substrate and method of producing same

A gallium arsenide single crystal substrate comprising a main surface having a circular shape, wherein

• the gallium arsenide single crystal substrate has R1, R2, R3, R4, R5, and R6, each of which is a first integrated intensity ratio,
• the first integrated intensity ratio is obtained by determining a spectrum of a detection intensity of a 3d electron of arsenic with respect to a binding energy of a photoelectron emitted to outside of the gallium arsenide single crystal substrate based on X-ray photoelectron spectroscopy in which X-ray is applied to a center of the main surface under each of below-described specific conditions,
• the first integrated intensity ratio is a ratio of an integrated intensity of an arsenic element present as diarsenic pentoxide to a sum of the integrated intensity of the arsenic element present as the diarsenic pentoxide, an integrated intensity of an arsenic element present as diarsenic trioxide, an integrated intensity of an arsenic element present as gallium arsenide, and an integrated intensity of an arsenic element present as a metal arsenic,
• the R1 is obtained by performing the X-ray photoelectron spectroscopy under a below-described condition 1,
• the R2 is obtained by performing the X-ray photoelectron spectroscopy under a below-described condition 2,
• the R3 is obtained by performing the X-ray photoelectron spectroscopy under a below-described condition 3,
• the R4 is obtained by performing the X-ray photoelectron spectroscopy under a below-described condition 4,
• the R5 is obtained by performing the X-ray photoelectron spectroscopy under a below-described condition 5,
• the R6 is obtained by performing the X-ray photoelectron spectroscopy under a below-described condition 6, and
• a relation in which at least one of the R2, the R3, and the R4 is the largest among the R1, the R2, the R3, the R4, the R5, and the R6 is satisfied, where the condition 1:
• X-ray incident energy of 150 eV and photoelectron take-off angle of 30°,
• the condition 2:
• X-ray incident energy of 150 eV and photoelectron take-off angle of 45°,
• the condition 3:
• X-ray incident energy of 150 eV and photoelectron take-off angle of 85°,
• the condition 4:
• X-ray incident energy of 600 eV and photoelectron take-off angle of 30°,
• the condition 5:
• X-ray incident energy of 600 eV and photoelectron take-off angle of 45°, and
• the condition 6:
• X-ray incident energy of 600 eV and photoelectron take-off angle of 85°.