PHOTODISSOLUTION PROFILE OF SILVER IN AMORPHOUS-CHALCOGENIDE GESEX THIN-FILMS

Ag photodissolution profile in amorphous GeSe(x) was investigated by secondary ion mass spectroscopy (SIMS), by Rutherford backscattering (RBS) and also by scanning electron microscopy (SEM). From SIMS measurements, Ag was found to exhibit generally a step-like profile in GeSe(x) (5.5 < x < 6.4) thin films deposited by plasma enhanced chemical vapor deposition on Si substrate but some samples show an intermediate Ag poor zone. RBS data show two Ag rich regions (one at the surface of the GeSe5.5 film and the other at the interface GeSe5.5/Si) separated by a poor one. In GeSe4 films evaporated on glass substrate such an anomalous effect is observed for the thin initial Ag layers. GeSe3 films evaporated on Si substrate exhibit a rather different behavior from SIMS as well as from RBS: Ag photodissolution is very much slower than in GeSe5.5 and the Ag profile is governed by a diffusion mechanism. SEM microprobe analysis confirms these results.