Durán Flores, Larissa, and Gerardo Fonthal. “Urbach”™s Tail in Indirect Band-Gap Semiconductors”. Rev. Téc. Fac. Ing. Univ. Zulia 26, no. 1 (1). Accessed August 2, 2025. https://produccioncientifica.luz.edu.ve/index.php/tecnica/article/view/5791.