Improvement on the onset voltage for electroluminescent devices based in a SiO x /SiO y bilayer obtained by sputtering

This work is focused on the composition, optical and electroluminescent properties of silicon rich oxide (SiO x , x < 2) films monolayers and bilayers (SiO x /SiO y ) deposited by Sputtering with silicon excess between 6.2 to 10.7 at.% were deposited on p-type (100) silicon substrates. As-deposited SiO x films emit a broad photoluminescence (PL) band where the maximum peak shifts from 420 to 540 nm as the Si-excess increases from 6.2 to 10.7 at.%, respectively. The PL intensity strongly increases and the main PL peak shifts to the red region when the SiO x films are thermally annealed. The PL emission band was dependent on silicon excess and the presence of Si-O bonds defects working as emission centers. MOS-like devices were fabricated (N+ polysilicon was used as top contact and aluminum as bottom contact) to study the EL of SiO x monolayers and SiO x /SiO y bilayers. It was found that the required voltage to obtain EL was reduced when SiO x /SiO y bilayers were used in light emitting capacitors (BLECs) as compared to those with SiO x monolayers.