Fabrication method of GaAs substrate

摘要

A GaAs semiconductor substrate (10) includes a surface layer (10a). When an atomic ratio is to be calculated using a 3d electron spectrum of Ga atoms and As atoms measured at the condition of 10° for the photoelectron take-off angle ¸ by X-ray photoelectron spectroscopy, the structural atomic ratio of all Ga atoms to all As atoms (Ga)/(As) at the surface layer (10a) is at least 0.5 and not more than 0.9, the ratio of As atoms bound with O atoms to all Ga atoms and all As atoms (As - O)/{(Ga) + (As)} at the surface layer (10a) is at least 0.15 and not more than 0.35, and the ratio of Ga atoms bound with O atoms to all Ga atoms and all As atoms (Ga - O)/{(Ga) + (As)} at the surface layer (10a) is at least 0.15 and not more than 0.35. Accordingly, there is provided a GaAs semiconductor substrate having a surface cleaned to an extent allowing removal of impurities and oxides at the surface by at least thermal cleaning of the substrate.