Annealing effects on SiOxNy thin films: Optical and morphological properties

Abstract

The annealing effect on the properties of silicon oxynitride (SiO x N y) thin films has been investigated. The present contribution aims to study the structural and optical properties of SiO x N y thin films deposited by plasma enhanced chemical vapor deposition in view of their application in the field of photovoltaics. Evolution of the surface morphology and increase of the optical band gap with the thermal treatment have been determined and discussed in view of the application of the film as an emitter layer in heterojunction solar cells.

Transport properties of Si based nanocrystalline films investigated by c-AFM

“…After the deposition, the annealing process promotes recrystallization of the nc-SiO x N y samples, demonstrated through an increase of the crystalline fraction [6]. In addition, thermal process induces clustering of grain-like structures on the sample surface and boosts the optical bandgap up to 2.5 eV [7].…”

“…The last enhancement is probably correlated to oxygen relocation due to the thermal treatment and formation of O-and Si-rich areas within the samples [6]. Moreover, annealing affects the surface morphological properties of the samples as well, that is, the surface roughness and the structures dimensions on the surface increase in the annealed samples [7].…”

“…SiO x N y doped layers are deposited with R B2H6 ¼ 2.34% and then annealed at 800 C in a nitrogen atmosphere to promote nanocrystals formation. SiO x N y doped samples revealed the presence of Si crystallized fraction [6,7]. We will call them nc-SiO x N y for sake of clarity.…”

“…SiO x N y doped layers are able to reach an energy gap of 2.5 eV and electrical conductivity of 44 S/cm [6]. Our recent studies have reported on the variation of nanoscale morphology and structural and compositional characteristics of these layers with different deposition conditions [6,7], showing annealing-induced phase separation, with a formation of Si-rich and O-rich areas due to oxygen relocation within the layers [6]. This separation, together with the increase of crystalline fraction upon annealing, has been related to the increase of the macroscopic conductivity [6].…”

Critical Level of Nitrogen Incorporation in Silicon Oxynitride Films: Transition of Structure and Properties, toward Enhanced Anticorrosion Performance

“…Moreover, many of the previously described applications involve heat-sensitive and/or 3D-complex structures. Common literature that targets low deposition temperature reports SiO x N y films that are amorphous and produced by plasma enhanced chemical vapor deposition (PECVD) processes. , However, increased hydrogen incorporation is often encountered in PECVD prepared films, which can be detrimental to barrier performance. As a cost-effective alternative, an atmospheric pressure thermal CVD process is proposed, operated using reactive chemistries complying with deposition at moderate temperatures, compatible with heat sensitive substrates such as glass.…”