Formation of luminescent (NH4)2SiF6 phase from vapour etching-based porous silicon

Silicon Porosification: State of the Art

“…[228][229][230][231][232][233] In CVE a solution similarly to stain etching is made up from concentrated HF plus concentrated HNO 3 . However, instead of dipping the Si substrate in the solution, the substrate is held above the solution.…”

Fabrication and electrical properties of Si/PS/ZnO:In solar cell deposited by rf-magnetron sputtering based on nanopowder target material

“…Porous silicon wafer was prepared with the vapor etching (VE) technique [28], using a bore-doped (100) oriented Si substrate (q = 2 X cm, N D = 5 9 10 15 cm -3 ) with mirror-polished surface. The VE method involves exposition of Si substrate to acid vapors issued from a mixture of HNO 3 and HF having a concentration of 65 and 40 %, respectively.…”

Porous Silicon Formation by HNO3/HF Vapor Etching

“…2). The morphological features of PS and (NH 4 ) 2 SiF 6 depend on the Si doping type, the temperature of the acid mixture, the temperature of the Si substrate, and on-time exposure to the HNO 3 /HF vapors (Saadoun et al 2002;Ben Jaballah et al 2004;Saadoun et al 2003). Obviously the diverse PS morphologies essentially depend on the doping type (Fig.…”

“…The detailed experimental conditions of VE have been studied by Saadoun et al (Yablonovitch et al 1986) and Ben Jaballah et al (2004); this technique enables generating PS and/or a luminescent white powder (WP) corresponding to the (NH 4 ) 2 SiF 6 compound; later this surprising luminescence was attributed to embedded SiOx/Si nanoparticles (Saadoun et al 2003). One of these two phases can be dominant depending on the HNO 3 /HF volume ratio.…”

“…Independently, Kalem and Yavuzcetin (2000) obtained light-emitting PS from the exposure of Si surface to gaseous etchants prepared from (HF:HNO 3 :H 2 O, 2:1:5) mixtures. Later, it was found that HNO 3 /HF vapor etching of Si can lead to the formation of PS, (NH 4 ) 2 SiF 6 , and Si/SiOx nanoparticles, depending essentially on the HNO 3 /HF volume ratio, the etching time, and the temperature of the HNO 3 /HF mixture (Ben Jaballah et al 2004;Saadoun et al 2003). In this chapter, we will give an overview on HNO 3 /HF vapor etching and focus on the physical and technological interests of this fabrication method.…”