Original Research Paper Silicon rich oxide powders by HWCVD: Its optical and morphological properties A. Benítez-Lara a , G. García-Salgado a , D.E. Vázquez-Valerdi a , A. Morales-Sánchez b , N.D. Espinosa-Torres a , J.A. Luna-López a,⇑ a CIDS-ICUAP, Benemérita Universidad Autónoma de Puebla, 14 Sur y Av. San Claudio, Ciudad Universitaria, Edif. 103 C o D, Col. Sn. Manuel, Puebla 72570, Pue, Mexico b Centro de Investigación en Materiales Avanzados S.C., Unidad Monterrey-PIIT, 66600 Apodaca, Nuevo León, Mexico article info Article history: Received 23 May 2014 Received in revised form 8 September 2014 Accepted 13 September 2014 Available online xxxx Keywords: SROP PL SEM Agglomerates abstract The effect of the growth temperature on the optical and structural properties of silicon rich oxide pow- ders (SROP) deposited by hot wire chemical vapor deposition is studied. Different microscopic and spec- troscopic characterization techniques were used, as photoluminescence (PL), Raman spectroscopy, scanning electron microscope (SEM) and UV–Vis spectroscopy. The powders emit a wide PL spectrum, and the maximum emission peak shows a strong intensity as the growth temperature increases. The SROP deposited at 449 °C showed the most intense peak in PL at 592 nm. The morphology of SROP sam- ples grown at 449 °C revealed the presence of grains with a big size product of coalescence. In low tem- peratures, the micrographs show small grains, similar to the frost, which it was shown by SEM. The Raman analysis shows that the SROP samples are amorphous except for the growth temperature of 449 °C which exhibit both amorphous and crystalline phases. UV–Vis spectra were used to determinate the optical band gap using the Kubelka–Munk ´ s (K–M) method. Diffuse reflectance (DR) spectra showed a wavelength-shift of the absorption edge, indicating an increase in the energy optical band gap, when the growth temperature decreases. According to these results, we have studied and analysed the evolution of the morphology of the SROP due to the supersaturation of the environment by the precursors, which affects the intensity of PL, the absorption edge in UV–Vis and the energy optical band gap. Ó 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved. 1. Introduction Silicon is the most important material in the microelectronics industry and since the discovery of room temperature PL of porous silicon by Canham in 1990 [1], silicon nanocrystals (Si-ncs) has been under intense investigation for the fabrication of photosen- sors, electrode of lithium ion batteries, photonic devices and so on [2–4]. The non-stoichiometric silicon rich oxide powders (SROP) are one of the materials based on nanostructured silicon and this kind of material can be used in membranes to capture the CO 2 from the air [5–7]. Recently, materials containing silicon nanocrystals have attracted the interest of researchers due to their optical prop- erties. For that reason, a great variety of materials with these char- acteristics have been studied [8–11]. Other of these materials is the non-stoichiometric silicon oxide (SiO x ), where the Si excess agglomerates to create Si nanoparticles embedded in an oxide matrix after a thermal annealing at high temperature. SiO x shows some special compositional, structural, morphological, and optical properties that vary with the Si excess. In particular, the optical characteristics of SiO x films can be varied with the growth temperature. SiO x powders have been obtained by different methods as: mechanical milling [12], Plasma Enhanced Chemical Vapour Depo- sition (PECVD) [11,13] and Sol Gel [5–7,14]. The HWCVD technique used in this work differs from conventional Cat-CVD, HFCVD and initiated-CVD; which consist in the thermal decomposition of reac- tant gases at the surface of a hot-wire [15,16]. HWCVD produces its gaseous precursors from the interaction of atomic hydrogen and a solid source of quartz. This peculiarity of the HWCVD technique makes it a potential alternative to obtain SROP with high growth rates at low cost. The rate of deposit is 7.9 lgr/s in an area of 1 cm 2 of substrate. Many different mechanism have been presented to explain the process that causes the visible PL as: (i) a quantum size effect in small crystals or surface sites in the particles themselves in nano- powders [17]; (ii) interfacial defects in networks Si/SRO [18] (iii) the effect of silicon hydride species passivating the surfaces [19] http://dx.doi.org/10.1016/j.apt.2014.09.005 0921-8831/Ó 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved. ⇑ Corresponding author. E-mail address: jose.luna@correo.buap.mx (J.A. Luna-López). Advanced Powder Technology xxx (2014) xxx–xxx Contents lists available at ScienceDirect Advanced Powder Technology journal homepage: www.elsevier.com/locate/apt Please cite this article in press as: A. Benítez-Lara et al., Silicon rich oxide powders by HWCVD: Its optical and morphological properties, Advanced Powder Technology (2014), http://dx.doi.org/10.1016/j.apt.2014.09.005