Ion-induced physical and optical densification in obliquely deposited Se0.75Ge0.25 films

Abstract
Irradiation of obliquely deposited films of Se0.75Ge0.25 with 50‐keV He+ ions produces enormous physical and optical densification. A thickness and hence volume contraction up to 39% accompanied by large changes (0.20 eV) in the band gap and refractive index (10.2%) have been observed. These changes are primarily due to the physical collapse of the low density columnar structure and associated electron‐phonon coupling. Such large changes have great potential applications in high resolution image storage, holography, and lithography.