Radiative Recombination at Ion-Induced Defects in CuSe.sub.2 Alloy Thin Films

• Published in: Semiconductors (Woodbury, N.Y.) N.Y.), 2021-02, Vol.55 (2), p.168
• Main Authors: Borodavchenko, O. M, Zhivulko, V. D, Mudryí, A. V, Yakushev, M. V, Mogilnikov, I. A
• Format: Article
• Language: English
• Subjects: Alloys; Comparative analysis; Dielectric films; Hydrogen; Optical properties; Photoluminescence; Radiation; Specialty metals industry; Thin films
• ISSN: 1063-7826
• DOI: 10.1134/S1063782621020093

Radiation-induced effects in Cu(In,Ga)Se.sub.2 alloy thin films after implantation with hydrogen ions with energies of 2.5, 5, and 10 keV and a dose of ~3 x 10.sup.15 cm.sup.-2 are studied. Comparative analysis of the optical characteristics of nonimplanted and hydrogen-implanted Cu(In,Ga)Se.sub.2 films is conducted on the basis of photoluminescence spectra and luminescence-excitation spectra recorded at liquid-helium temperature (~4.2 K). The band gap determined for Cu(In,Ga)Se.sub.2 alloys by mathematical processing of the luminescence-excitation spectra is ~1.171 eV. In the photoluminescence spectra of nonimplanted and hydrogen-implanted Cu(In,Ga)Se.sub.2 films, an intense band is detected, with a maximum at ~1.089 eV. The band is defined by the recombination of free electrons with holes localized in the valence-band tails. It is established that broad bands with maximums at the energies 0.92 and ~0.77 eV are defined by the radiative recombination of nonequilibrium charge carriers at deep energy levels of ion-induced acceptor defects formed in the band gap of Cu(In,Ga)Se.sub.2 alloys. The conditions for the effect of the ion passivation of dangling electron bonds at the surface and in the bulk of polycrystalline Cu(In,Ga)Se.sub.2 films and the nature of structural point defects and the mechanisms of radiative recombination are discussed.