SiO x /SiN y multilayers for photovoltaic and photonic applications
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NANO EXPRESS
Open Access
SiOx/SiNy multilayers for photovoltaic and photonic applications Ramesh Pratibha Nalini1*, Larysa Khomenkova1, Olivier Debieu1, Julien Cardin1, Christian Dufour1, Marzia Carrada2 and Fabrice Gourbilleau1
Abstract Microstructural, electrical, and optical properties of undoped and Nd3+-doped SiOx/SiNy multilayers fabricated by reactive radio frequency magnetron co-sputtering have been investigated with regard to thermal treatment. This letter demonstrates the advantages of using SiNy as the alternating sublayer instead of SiO2. A high density of silicon nanoclusters of the order 1019 nc/cm3 is achieved in the SiOx sublayers. Enhanced conductivity, emission, and absorption are attained at low thermal budget, which are promising for photovoltaic applications. Furthermore, the enhancement of Nd3+ emission in these multilayers in comparison with the SiOx/SiO2 counterparts offers promising future photonic applications. PACS: 88.40.fh (Advanced materials development), 81.15.cd (Deposition by sputtering), 78.67.bf (Nanocrystals, nanoparticles, and nanoclusters). Keywords: SiOx/SiNy, multilayers, Nd3+ doping, photoluminescence, XRD, absorption coefficient, conductivity
Introduction Silicon nanoclusters [Si-ncs] with engineered band gap [1] have attracted the photonic and the photovoltaic industries as potential light sources, optical interconnectors, and efficient light absorbers [2-5]. Multilayers [MLs] of silicon-rich silicon oxide [SiOx] alternated with SiO 2 became increasingly popular due to the precise control on the density and size distribution of Si-ncs [6,7]. Moreover, the efficiency of light emission from SiOx-based MLs exceeds that of the single SiO x layers with equivalent thickness due to the narrower Si-nc size distribution. The ML approach is also a powerful tool to investigate and control the emission of rare-earth [RE] dopants, for example, Er-doped SiOx/SiO2 MLs [8]. It also allows us to control the excitation mechanism of the RE ions by adjusting the optimal interaction distance between the Si-ncs and the RE ions. However, achieving electroluminescence and hence extending its usage for photovoltaic applications are problematic due to the high resistivity caused by SiO2 barrier layers [9]. Hence, replacement of the SiO 2 sublayer by alternative * Correspondence: [email protected] 1 CIMAP UMR CNRS/CEA/ENSICAEN/UCBN, 6 Bd. Maréchal Juin, 14050 Caen Cedex 4, France Full list of author information is available at the end of the article
dielectrics becomes interesting. Due to the lower potential barrier and better electrical transport properties of silicon nitride [Si3N4] in comparison to SiO2, multilayers like SiOx/Si3N4 [10], Si-rich Si3N4 (SiNy)/Si3N4 [11], and Si-rich Si3N4/SiO2 [12] were proposed and investigated [13] for their optical and electrical properties. In this letter, we investigate SiOx/SiNy MLs and compare them with the SiO x /SiO 2 counterparts reported earlier [9,14]. We demonstrate that an enhancement in the conductive and light-emitting propert
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