Frustration of photocrystallization in amorphous selenium films and film-polymer structures near the glass transition

We investigate the stability against photo-induced crystallization (PiC) and photo-induced darkening (PiD) in a series of amorphous selenium (a-Se) films grown with and without polyimide buffer layers[1] for temperatures below and above the glass transition (T_g ∼ 313 K). The a-Se films are bulk-like (∼16.5 μm thick), and contain a low concentration of As (< 0.2%). We find that due to strain relief, a thin layer (∼1 μm) of polyimide greatly stabilizes the samples against PiC and reduces the effect of PiD.