C. Alejo-Armenta, C. Vázquez-López, G. Torres-Delgado, J. Mendoza-Alvarez, ., and J. Alvarado-Gil, “Photoreflectance of intrinsic GaAs epitaxial layers grown by LPE with supercooling”, Rev. Mex. Fís., vol. 39, no. 6, pp. 924–931, Jan. 1992.