Chemically Bath Deposited Sb2S3 Films as Optical Phase Change Materials

This paper presents the experimental results of laser-induced phase changes in chemically bath deposited (CBD) Sb2S3 films on fused silica glass substrates. The CBD allows conformal coverage of the glass substrate with surface roughness of 21.8 nm as estimated from AFM. As deposited Sb2S3 films show an amorphous-like structure as was revealed by both green laser (λex=514 nm) Raman and FT Raman (λex=1064 nm) spectroscopy. Optical transmittance indicates that the absorption edge in Sb2S3 films is 550 nm and therefore light below this wavelength will be strongly absorbed. Above certain threshold power, 2mW, of green laser (λex=514 nm) we observe that we can trigger an amorphous to crystalline phase transition in Sb2S3 films. Following this transition, we have also observed the appearance of α-Sb2O3 and the metallic Sb in the Sb2S3 films. The changes in optical properties have been investigated by spectroscopic ellipsometry.