A Cost-Effective Growth of SiO_x Thin Films by Reactive Sputtering: Photoluminescence Tuning

摘要

We present a new cost-effective method to produce substoichiometric SiO_2 thin films by means of a simple sputter-coater operated at a base pressure of 1 × 10~(-3) mbar. During sputtering air is introduced through a fine valve so that the sputtering gas is a mixture of air/Ar. High-resolution electron microscopy shows the formation of amorphous SiO_x thin films for the as-deposited samples. The index x approaches 1 when the ratio of the partial pressure of air/Ar tends to 0.1. On the other hand, pure silica is formed when the ratio of the partial pressure of air/Ar approaches 0.5. The films in the as-deposited state show intense green-yellow photoluminescence. This fades away with short annealing under air at 950℃. If on the other hand, prolonged annealing is performed under Argon atmosphere at 1000℃, red-infrared photoluminescence is recorded due to the formation of Si nanocrystals embedded in SiO_2. This simple method could be suitable for the production of thin SiO_x films with embedded nanocrystals for optoelectronic or photovoltaic applications.