Provided is a laminate containing a first compound semiconductor layer; and a second compound semiconductor layer integrally bonded to the first compound semiconductor layer via a bonding layer. A plane A is in the second compound semiconductor layer bonded to a surface where a plane B is in the first compound semiconductor layer, or a surface where a plane B is in the second compound semiconductor layer bonded to a surface where a plane A in the first compound semiconductor layer. The impurity concentration of the bonding layer is 2×1018 cm3 or more.